I know grung are not part of the PHB+Tasha's, but I really like the idea of a frogman in the rigging of a ship.
You are free to dismiss the idea, but here goes:
Everyone in the harbor of Evermoor knows Ploo Ploo, even though few know his name. The grung stands out with his bright colours and, more importantly, the assortment of tiny poison dart frogs following him around everywhere.
When Ploo Ploo is not rescuing various small animals from the perils of ships, smugglers and malnourishment, the little grung helps load and unload cargo from ships. But he dreams of being a sailor one day, climbing the ropes and jumping from one mast to another as they sail towards the horizon!
Being found as a tadpole by a druid, Ploo Ploo never knew the grung tribe he came from. Perhaps one day he will find them, although part of him fears how they will treat him...
Mechanically, Ploo Ploo is a grung swarmkeeper ranger, with (probably) the sailor background. If Leatherhead is up for it, his druid could be the one that found Ploo Ploo as a tadpole.