We have 3 days in Lyon in April. We are interested in any/all things food related. What is open on Mondays?
It's mainly museums and historic sites that are closed in France on Mondays. A few very traditional small shops will be closed on Monday mornings, but are usually open in the afternoon. A small number of restaurants may be closed on Mondays (usually if they are open on Sunday) but it's not a general thing and you just need to check individual restaurants that you particularly want to visit.
As a former Lyon resident, this strikes me as an odd question. The most notable thing I noticed living in Lyon about Mondays is that a few restaurants are closed and that it's hard to buy fresh fish on Mondays because many fishmongers are closed on Monday.
So the short answer to your question is: practically, but not quite, everything.
Thank you very much. I feel much better about th days that we chose!