On android we have this ui to choose what file format to save as.
I suggest that to the left of the name should be a little star (the favourite button) and when you press that the action it then starts appears at the top of the list .
By default there could be a few already favorited like:
- KRA
- PNG
- JPEG
- WEBP (i know but it is so commonly used)
- AVIF
- GIF
a sear bar would also be handy