I would take a look at the List of the different
MVS Multi carts and order the one that you can get and suits you the most
They are far from perfect, and they differ in the selection of games, but many(all) also contain the some shitty hacks to bolster the game count.
Shock troopers and Nam are on only on the 120 and the 138 in one, Magician Lord isn't on any of these carts.
I had the the 138 in one and with a little modding it was pretty good for the price. With that one i would mod it with a dip switch, that way you don't need the extra pcb for game selection. I think i got mine from aliexpress at the time.
If i remember correctly the 138 in one with modding was the best way to go.
But once you switch to a proper multi you'll probably never go back.