if you can think of it, there is likely some way to implement it. it’s always just a matter of how costly it would be to build and maintain. i think it would be a stretch to ask iNat staff to specifically add a visualization just for ecoregions in its maps, especially with interactive functionality, because that seems like it would be a lot of work to do something that – to me – seems relatively far from the core mission of iNat. but who knows? maybe they will decide that it’s worth the effort to do it. (personally, i probably would never use such functionality, or if i did, i would use it only very rarely.)
a web search is going to provide you better advice than i could provide here.