@kjr @alex Yep! So #Soapbox was originally a fork of #Gab which was a fork of #Mastodon. It eventually was rebuilt by forking #Pleroma and retaining the existing #Soapbox frontend, and now the #rebased backend and #Soapbox (the frontend) have been split apart, with (IIRC) the intention of #Soapbox being a multipurpose frontend that can be used with different #Fediverse software, and #rebased being a lightweight #Fediverse backend software.
You can visit fe.soapbox.pub to check out #Soapbox and try the software with your instance! It works quite well with #Mastodon and #Pleroma especially, I can't remember if it supports #Misskey at all.