It appears (from a glance at the museum's website) that the Hunterian is open.
I enjoyed tracking down Glasgow's Charles Rennie Mackintosh buildings. The Glasgow School of Art remains closed following two absolutely disastrous fires, but the House for an Art Lover is open; check here for hours: https://www.houseforanartlover.co.uk/visit/opening-times-admission-prices. There seem to be special events scheduled for Friday and Saturday afternoon, so it's only open in the morning on those days.
Alternatively, you could hop on a train to Helensburgh and see the Hill House. I believe there are two train stations in Helensburgh. It's worth checking Google Maps to see which is closest to the Hill House; even so, there will be a bit of a walk. I don't know whether there are city buses.
The Botanic Garden in Glasgow is supposed to be nice. I walked past it but didn't have time to go inside. Weather-dependent for normal human beings, I'd say.
The Glasgow Necropolis was an interesting place to wander on a day with nice weather. It's up on a hill, so I guess it could be sort of miserable on a cold, wet, windy day.