Kigeli Magnetic Card Game Deck... https://www.amazon.com/dp/B0BMV95K8J?ref=ppx_pop_mob_ap_share

I use this. Holds 5 commander decks in Boulder cases, counters, dice, etc. I wrap an elastic cord around it to keep it closed if I'm putting it in a bag etc, but don't do that very often, usually just carry it in from the car.

I don't use a play mat, but there is space for one that I take up with other stuff.