Hi Steve and others with interest in wiki.debian.org! I wanted to follow up on this thread and advertise that Steve is running a BoF session about the wiki future at DebConf: https://debconf25.debconf.org/talks/146-debian-wiki-bof/
I've added some of the people who participated in https://salsa.debian.org/debian/grow-your-ideas/-/issues/2 and who's email address I have easily available as CC here, and I've posted a note about this BoF in that issue. I have also added some research about potential Markdown+git software in https://salsa.debian.org/debian/grow-your-ideas/-/issues/2#note_288815. Maybe you Steve could invite people to the BoF in advance to ensure there is good attendance at least by the people who have publicly committed they would be willing to work on upgrading/migrating the wiki? I probably won't have bandwidth to help with the software part, but feel free to add me as co-organizer in the BoF if you want further help with the BoF session itself.
