The Redream emulator for Sega Dreamcast, is available on the google playstore. I know people struggled with setting up the standalone Reicast emulator, Redream is far easier. No extra BIOS files are required and it detected my gamepad straight away, even found the game files!
I have asked about launch intent, so the app is compatible with frontends like Hyperspin and Arc Browser. The reply I got was he meant to add the feature last night but "forgot" as inundated with day one crash reports. Once the feature is implemented, I'll do a video showcasing the emulator and show my settings.ini for Hyperspin