You can save seeds from hybrids too. Just understand that they *likely* will not come true.
That’s not always the case. The ‘Campari’ tomatoes you see for sale in the little plastic clamshells at the grocery store will come true something like 97 or 99 times out of 100.
Other stuff, like the Sungold variety of cherry tomatoes are notorious for not coming true. YMMV. They will all be tomatoes though. And they will all ‘eat’. Just not necessarily what you expected. If TSHTF grocery store tomatoes could be used for seeds if you didn’t have any other seeds on hand or your neighbors wanted to grow tomatoes too.
Do tomatoes have to be picked as ripe for the seeds to mature? I know this is the case with pepper plant seeds and others too. Last winter I must have thrown an old, rotten tomato into the tree bed since I got a few seedlings I have since transplanted. Should be interesting to see what variety they are— I think Roma but time will tell.