I’d like to use both, with preferably the same account, but mainly the same android app
mbin is probably the closest to what you want. Its supports both threaded content (lemmy) as well as microblogging (mastodon) Here is a list of servers https://joinmbin.org/servers and interstellar is the mbin app.
Honourable mention to piefed.social / pyfedi which can do both as well.
However, it’s newer than mbin and I’m not sure about mobile apps working with it.
Someone creates a version which adds a Lemmy compatible api to pyfedi and tested out a couple of mobile apps against it, https://codeberg.org/rimu/pyfedi/issues/13#issuecomment-1814982
So it’s not impossible - but it’s also very much a YMMV thing (I suppose it’s really still only for developers atm)
