HN user
Matrix is only a protocol. There are some clients listed for it on this page: https://matrix.org/docs/projects/try-matrix-now.html
Whatever you plan to use it for, those projects should have communities of people to help.
When you say Debian has nicer wifi UI than OpenBSD, isn't that dependent on the DE? You never mentioned which DEs you use. If you run the same DE on both, does it look noticeably different?
Can you solve equations on it? I tried on the online simulator and even looked through the manual but it doesn't seem to have it.