Yes, Lemmy in open source FOSS project, so is the Android app (Jerboa).
There is another iOS app that is still in beta I think, it's called Mlem.
Jerboa is a native-android client for Lemmy, built using the native android framework, Jetpack Compose.
Warning: You can submit issues, but between Lemmy and lemmy-ui, I probably won't have too much time to work on them. Learn jetpack compose like I did if you want to help make this app better.
Jerboa is made by Lemmy's developers, and is free, open-source software, meaning no advertising, monetizing, or venture capital, ever. Your donations directly support full-time development of the project.
1Hefs7miXS5ff5Ck5xvmjKjXf5242KzRtK
0x400c96c96acbC6E7B3B43B1dc1BB446540a88A01
41taVyY6e1xApqKyMVDRVxJ76sPkfZhALLTjRvVKpaAh2pBd4wv9RgYj1tSPrx8wc6iE1uWUfjtQdTmTy2FGMeChGVKPQuV
addr1q858t89l2ym6xmrugjs0af9cslfwvnvsh2xxp6x4dcez7pf5tushkp4wl7zxfhm2djp6gq60dk4cmc7seaza5p3slx0sakjutm
Yes, Lemmy in open source FOSS project, so is the Android app (Jerboa).
There is another iOS app that is still in beta I think, it's called Mlem.
Did you even try to search for the project? https://github.com/dessalines/jerboa You can find the licence and everything in there.
For the rest no idea, I'll let the dev answer if anything.