If you have a thunderbolt 3 port then the apple adapters are reasonable second-hand, but you need a tb3->tb2, and tb2->firewire adapters. They work fine in Wind

If you have a thunderbolt 3 port then the apple adapters are reasonable second-hand, but you need a tb3->tb2, and tb2->firewire adapters. They work fine in Windows and Linux. OWC used to make TB docks with firewire, but they're rare and expensive now. Anything that claims to adapt plain USB to firewire is bait for unsuspecting buyers, or maybe supported by some ancient obscure sony camcorder models. The cheapest options for firewire these days are pci, cardbus, pcie, and expresscard in about that order. G3/G4 era macs up to 2012 models are common firewire machines. I know Sony and IBM had laptops with the interface in the core duo times.