I would stay in the airport, airside. The AM lounges are not very good, but I've only been to them no more than a couple dozen or so times, so maybe I'm not the best one to give advice. The one I do like best (for relaxation, not for food selections) is the AM Heineken Terraza - it is far out by Gate 75, and is a bright and much more tranquil space than the other two AM lounges. Just opposite that in the same area is a Priority Pass lounge, which I was going to check out a few weeks ago, but didn't have much time. The Salon Aeromar is not worth the bother, although I've not bothered in a few years, so maybe, just maybe, there's more than a bag of chips or a snackiecake. I've never consumed non lounge food at MEX, so I can't guide you to a restaurant, but maybe someone makes a good taco.
If you want to leave the secured area but have a convenient and perhaps decent option (I have no personal experience with this) is visiting the NH Hotel restaurant within T2 (landside).
Note that in recent weeks, there have been some taxi protests completely blocking car access to the airport.
Finally, your 4:15 connection is will really only be three hours - you should probably be at the SFO gate an hour early so you can have your "interview" with an orange vest person verifying docs and asking you a few security questions. And then you've got five lounges you can visit.