There are several tile coating systems out there, that use a binding primer. I don’t know if they’re safe for food contact, as some kitchen counters are tiled.
I would tile over the top of them myself. Porcelain mosaics are easy to cut with “nibblers”. Wet tile saws start at $80 and pro grade saws are $70 a day to rent.
If you go this route, lmk and I’ll explain how to epoxy on the new tile and which grout to use.
Here's a post that might help you - https://homeguides.sfgate.com/give-old-tiles-fresh-look-36491.html
Paint them!! Use a good primer and paint and then a sealant
Here's a great post on painting tile counters.