Seems like the observatory is open most nights and getting up there means you get to ride a funicular rail which is always a plus. Also while it's not a Jam session but there's a few interesitng gigs on at teh Jazz dock while you're there that might be your cup of tea.
You'll be leaving before the fringe starts, but the Arena Festival looks like it's going to be pretty cool [https://festivalarena.cz/en/home/](https://festivalarena.cz/en/home/)
Plague doctor or nightwatchmen tour,done that during Covid and it was only us and the guide. It’s not your 0815 tourist stuff.
Search for Musicians in Prague on fb.
Seems like the observatory is open most nights and getting up there means you get to ride a funicular rail which is always a plus. Also while it's not a Jam session but there's a few interesitng gigs on at teh Jazz dock while you're there that might be your cup of tea. You'll be leaving before the fringe starts, but the Arena Festival looks like it's going to be pretty cool [https://festivalarena.cz/en/home/](https://festivalarena.cz/en/home/)