Many proprietary packages can be simply removed. Others may be need to be
modified or replaced. For example, any proprietary firmware removed should be
replaced with with free firmware when available so that as many devices as
possible are supported. Another example is SMPLayer, which in Ubuntu (I think)
includes the non-free SMTube for YouTube compatibility, while the rest of
SMPLayer is free software. Rather than throw the whole thing out, it is better
to rebuild it without the proprietary feature. Then there's Firefox, which is
technically free software but has some problems that Abrowser attempts to
address. Things like these are why removing proprietary software is not as
simple as removing them from the repo. However, it seems to me that this is
mostly complete and that the main issue blocking the official release is
ensuring that the upgrade process from T7 to T8 is smooth no matter how T7 is
configured. I'm no expert, but I wonder if replacing GNOME Fallback with MATE
as the default DE makes this a particular challenge.