It’s really your call. Food before age 1 is just for fun! You could definitely give him supper if you feel you need to, I’d maybe wait like 15-30 minutes when he’s down for his belly to settle? But as long as he’s getting milk he wouldn’t NEED really food per se.
Upping the milk is more than fine. You may notice an extra wake up for milk as it's easier and quicker to digest than table food.
It’s ok! It’s happened to us before to, my baby is almost 10 months and this week we took her to urgent care for a rash and thought we’d be back in time for dinner. We got home super late and she was already tired so we just skipped dinner and fed her a bottle as normal. You can just resume normal feeding schedule the next day :) Formula or breastmilk is still their main source of nutrition before 1yo so skipping one meal today won’t hurt. If I were to feed baby late tho, i’d try to keep them up atleast 30-40 mins longer to let everything digest or if you really feel like it’s necessary, you could offer something small and light! 🩷