With help from @rojinroy@poddery.com we can now install #diaspora on a Debian 11 #bullseye system using native #debian packages using my personal repo as documented in https://wiki.debian.org/Diaspora#Bullseye_Backports.2Fpersonal_repo
Once bullseye is released by end of this month (hopefully), we will be able to upload it to official bullseye-backports.
We have been working on a diaspora package suitable for inclusion in Debian's main section for many years. A package in main should not depend on anything outside main to build or run. So we had to package all rubygems and rebuild all JavaScript libraries from their original source which involved packaging many nodejs build tools including grunt, gulp, babel, npm, yarn, webpack, rollup, typescript ...
We currently have a diaspora-installer in contrib section which downloads ruby dependencies from rubygems.org during installation and configures database, web server and TLS certificate with a few interactive questions.
I was able to get it working on buster-backports earlier but bullseye (Debian 11) moved to rails 6 and diaspora is not yet updated to work with rails 6. Finally I embedded rails 5 in diaspora and uploaded it to experimental.
I'd welcome more testing before I can recommend this to users.
See https://wiki.debian.org/Diaspora#Experimental for installing this version.
Currently libjs-autosize version in bullseye is broken and you need to manually install the version in buster as mentioned there. Help in fixing this bug is welcome (basically we need to find the correct babel 7 option to generate the same file that babel 6 generates).