Great city. If you can take a day trip to San Sebastian its worth it. If you were driving, you could go to Gaztelugatxeko on the way too (a filming location for Game of Thrones but impressive even if you have never seen the show).
The bars and restaurants will be open, not sure if there will be restrictions on other tourist things like the Guggenheim or a tour of the San Mames, but I'd have thought they would want to make money too, even if its reduced capacity.
I'm intending to go to Lisbon in August and accept there is some risk, but I believe its less than going to the supermarket or a pub here. Its a decision which affects me though and appreciate its different as you have to think about your lad too. There is risk in traveling at the minute, but I think its reduced risk at this stage, and its not going to go completely away for a while. I feel like I need to go abroad.