I have (literally) two milk crates full of old firewire drives, LOL. 😂 Finally archived them all to a pair of 5tb USB 3 hard drives around 5 years ago. I have the thunderbolt to firewire adapter in the link above, used it with my 2011 and 2013 MacBook Airs. It works fine, but it gets surprisingly hot - almost too hot to hold in your hand. This happens whenever the adapter is plugged in, even when no disk is connected to it. So, it is fine for a data transfer but maybe not a good solution for continued use.
Honestly, if you just need to do a one-time transfer from your old disk(s), just use the USB port and be happy. I'm sure you can find something to do for a few hours. That is what I started doing with my old disks before I archived them, it was just easier. And how fast is the drive inside that old firewire enclosure? Firewire 800 was only 100MB/sec maximum, many drives were not that fast. USB 2 typically gave me around 30-35MB/sec when I used it.
I wouldn't waste money on adapters or enclosures unless you are going to need them often in the future.