Two routes for open source apps: Zap Store and Obtainium. Zap store is easier, Obtainium involves pasting GitHub repo links and installing directly from there.
For regular apps, install the Aurora store and use it as a play store replacement.
https://zapstore.dev/
You can get aurora on zap store: https://zapstore.dev/apps/naddr1qqgxxmmd9esh2un0wfsjuum5daex2q3q0r8xl2njyepcw2zwv3a6dyufj4e4ajx86hz6v4ehu4gnpupxxp7sxpqqqplqkgu3xl9
