[Throwawayaerlei]

There are others, Pleroma was explicitly designed to be lightweight for small nodes, written in Elixir and thus running on the battle tested Earlang ecosystem BEAM VM. Also have heard and run across a few instances of Misskey which runs on node.js. Both use Postgres and I see from the install instructions the latter also uses Redis. Have heard of others as well but have no idea at all about them, a search on the above two backends will find you more.

You've also got some choices in front ends, I know Pleroma supports several. I strongly recommend not using Soapbox for a variety of reasons unless you really like its UI.