Consider the Engel ~60qt for the X which will serve as both a refrigerator and a freezer.
The largest that will fit in an S is the 40qt and I recommend the marine version thereof for that purpose. It serves as *either* a refrigerator or a freezer.
Given that the X has more headroom, the larger size makes sense. On the other hand, it’s possible that the 40qt could fit in the X frunk. Interesting option, especially since the S now has just a microfrunk.
Any Engel uses very little power and has only one moving part (swing compressor).
I’d suggest getting whichever model you choose from West Marine and getting the walk-in replacement warranty. Not because they fail, but because if you do get a bad one, it’s an easy swap with no shipping hassle. For inland, Bass Pro Shops might be an option.
A remote temperature sensor and wireless display kit is useful. I keep the display in the console. Temperature is maintained within 1-5 degrees depending upon the time of year.
Lastly, you’ll want a dedicated fused 12V receptacle and cable run from the fuse box for this. As long as you’re doing that, consider a Y at the end to have a spare 12V source in either the trunk or frunk depending upon where you choose to have the fridge/freezer.