How do I develope apps for Linux Smart phones?

Hi, I was wondering. iOS ans Android development is a pain in the ass, and requires (for the most part) some sort of native framework and language to make them work on those platforms.

I was wondering. How is development for Linux phones? I am guessing you would have to develop to the specific OS branch, like /e/os or PostmarketOS, to make it work on each devices, or is there a common language that just makes it executable for all linux platforms, so I only have to develop and deploy once, and then I will be able to put it on Ubuntus marketplace, etc? Anyone in here got any experience with this?