Here is a copy of our house rules. So far we have played 30+ sessions with them. Players are having great fun, and so far they have achieved the kind of game my players and I want. Our tables are a blast, and people must enjoy the game as I have players from the 80s and 90s still coming back for more. My players even read my 20-page guides for each campaign and work details into their backstory, I am a Blessed One DM!
I am sure some people will not like them, or not see what our table was going for (more OSR/gritty/slow healing). That said, I post them as an example for the OP, and I will
not be replying to every nit-pick that some of the illustrious commenters will provide, especially the line-by-line reply

I am not sure why certain parts are bolded or larger font below, it means nothing.
Uncommon/Rare Trait
Anything with the Uncommon or Rare trait is usually not selectable. Exceptions will usually be spells or magical items given by the DM and specific ancestries for a campaign.
Ancestry / Heritage
Players choose an Ancestry from the list provided for each campaign, as not all ancestries are available for every campaign. Descriptions of all the main ancestries follow these rules.
Ability Scores - Gradual Boosts
This variant from the Gamemaster’s Guide giving boosts earlier but more slowly is used.
Classes / Archetypes
Players can choose between a Free Archetype or Ancestral Paragon for their characters. Only one archetype or paragon path is permitted per character throughout its lifetime.
Classes - Divine Classes
Divine character classes always venerate one main deity, even if this contradicts the class description. This includes Champions, Clerics, Druids, Oracles, & Rangers.
Skill - Investigation
Investigation is an Intelligence skill, and it covers the Search and Investigate actions. Thus not tied to class/Perception.
Skill - Insight
Insight is a Wisdom skill, and it covers the Sense Motive action. Thus not tied to class/Perception.
Skill - Crafting
When a character selects Crafting, they must specify what specialty their skill refers to. Examples include alchemy, armorsmithing, weaponsmithing, jewelry, scribing, brewing, and so on. Characters can take multiple instances of Crafting if they want to be able to craft multiple types of items. Additionally, crafting does not take 4 days, but rather takes time-based on the Earn Income chart to get to 50% completion.
Skill - Medicine / Treat Wounds
Treat Wounds can only be used once per battle (this includes Battle Medicine), not every hour. If there is no encounter during a given day, it can be not used more than once per day.
Skill Action - Identify Magic
This action requires the use of read aura or similar spell. A critical failure means you cannot try to identify the magic again until you gain a level.
Feats - Uncommon
Adopted Ancestry, Blood Component Substitution, Continual Recovery, Craft Anything, Inventor, Red Herring, That’s Odd
Initiative - Reactions / Flat-footed
When combat starts, combatants cannot take reactions until their first turn in combat. If they failed Perception checks against hidden foes, they are flat-footed until they have their first turn in the round.
Action - Attacks of Opportunity
All PCs gain the Attack of Opportunity feat for any melee attacks they have Expert proficiency in. Creatures and NPCs gain the feat in a similar manner dependent on their level and role.
Action - Ready
A Readied action that causes damage disrupts manipulate actions on a critical hit. Additionally, two-action activities can be readied, and this costs three actions instead of two.
Action - Counterspell
Counterspell is available to all spellcasters as a 1st level class feat. Counterspelling does not require the exact spell to counter but instead requires a spell of the same school and level.
Condition - Wounded
The Wounded condition is only removed by a full rest, reducing the score by 1 point per 24 hours. The Diehard feat allows two points per 24 hours instead.
Prepared Spellcasters - Spell Preparation
Spellcasters that prepare spells (Clerics, Druids, Wizards, and Witches) have the Flexible Caster archetype abilities without the loss of spell slots or cantrips. Spells can be heightened during casting freely. Conversely, prepared spellcasters need to learn spells in a similar way to a wizard. Prepared spellcasters do not start out able to select any spell from their spell lists. Instead, you start with a spellbook worth 10 sp or less which you receive for free and must study or pray to prepare your spells each day. The spellbook contains your choice of 10 cantrips and five 1st-level spells from your class’s spell list. Each time you gain a level, you add two spells to your spellbook, of any level you can cast. You can also use your spellcasting skill to add other spells to your book.
Spontaneous Spellcasters - Signature Spells
Spontaneous spellcasters (Bards, Oracles, and Sorcerers) treat their spells as if all of their spells known are signature spells. Additionally, any bonus spells they get from bloodlines or other class features do not count towards their spells known.
Spells - Somatic Components
Spells with somatic components need an empty free hand to cast.
Spells - Focus Spells & Healing
Focus spells that provide healing can only be used on a creature once per day. This includes spells like Lay On Hands, Goodberry, Hymn of Healing, Life Boost, or any other spells that are similar.
Spells / Companions / Familars
Any summoned creatures or otherwise controlled creatures must be discussed and created in Foundry with the GM prior to any session.
Spells - Rituals
The primary caster of a ritual must have the ability to cast spells at a caster level appropriate for the ritual.
Spells - Spellstrike / Magus
The Spellstrike action does not draw Attacks of Opportunity.
Magical Items - Stores / Frequency
Magical items are far less common in Mazariim than other settings, and players should not expect to have the standard amount of Pathfinder 2E items. Balance issues will be handled by the GM. Magical items are almost never available for purchase in stores, the exceptions being low-level consumables and the most basic of magical weapons and armor.
Magical Items - Runes
Runes used on magical item creation are not transferable or upgradeable. When a magical item is completed, it cannot be altered any further.