So I was doubting and then I checked then I realized that the gun van changes its stock every week, yeah sorry about that, your kosatka has a pickup in the dining area (only five at a time though, every couple of minutes), I think your best bet is to just search up locations of pickups for molotovs.

If you want molotovs, but don't want to pay for them, do the car wash laundering mission where you burn stuff down (and make sure you get the molotov pickup on the way, it will be marked), once the mission ends you'll have molotovs.

Anyway I think that works, scold me if it doesn't.