there was a non foss one i used (iirc nodevideo? smth like that) but it wasn't great.

i recommend kdenlive in termux

bunny media editor ☞ https://f-droid.org/packages/eu.artectrex.bunny/

you can try CutWire Drift on the website https://cutwire.org/drift or librecuts, which is located in f-droid

Text on video in play store is great. Does have ads but only once video is created and third party shares with Google.

Maybe there's a way to run some desktop apps through FEX?

*slop source

open source needs to be better