Obtainium

I use Aurora

I use both. Obtanium is a good option to install things from github

I use f droid and obtainium, and aurora is good as well as others suggest. As well, if you want to do graphene on "beginners's mode," you can use the play store by enabling Google play services in sandboxed mode on graphene. You won't get full cypherpunk points for this, but it can make the transition easier at first