Well crap. The local #motorcycle shop checked out my bike. Synchro mesh seems to be gone in the gearbox, for sure between first and second the mechanic says, but I think also between the other gears, because the gear lever won't return to an engaged position when downshifting from any gear...
So that's the sad end of the #framo25 tour. I am limping the bike to a nearby depot where I'll get a rental car which I'll drive home. The bike is going to be transported home at some point... Sadness.