Tracking “Nala – APT on Steroids” article should help there, should help you. Also, please let us know if this guide helped you to install (easy one) and in particular how the nala package works for you. Thanks for the linked info/video (although didn’t watch it, not yet)! Actually linked article self-defines that this package doesn’t come from Debian 11 repo (therefore …).
I took an educated guess and opted for the nala_legacy package, and that seems to have been the correct choice. It’s working, although I do get the odd flatpack error here and there.
Nala legacy package installation fails. Proceeding with workaround method.
$ sudo apt install ./nala-legacy_0.11.0_amd64.deb
[sudo] password for purism:
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Note, selecting 'nala-legacy:amd64' instead of './nala-legacy_0.11.0_amd64.deb'
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
nala-legacy:amd64 : Depends: libc6:amd64 (>= 2.29) but it is not installable
Depends: libexpat1:amd64 (>= 2.1~beta3) but it is not installable
Depends: zlib1g:amd64 (>= 1:1.2.0) but it is not installable
Depends: apt:amd64 but it is not installable
Depends: python3-apt:amd64 but it is not installable
Depends: libpython3.9:amd64 but it is not installable
E: Unable to correct problems, you have held broken packages.