There are a bunch of USB-A to Firewire cables on Amazon. I wasn't even aware some Firewire devices also support USB over the same connector. Judging by the reviews some customers weren't aware that many or most Firewire devices don't.
DON'T GET ANY OF THOSE! They are pretty much just a scam, or they are only designed to provide an electrical charge to old FireWire iPods (but no syncing).
But yeah, if you're stuck with Tahoe, I recommend you buy an older Mac that DOES have a FireWire port and use that to import the footage. I have a collection of older FireWire-enabled Macs that can get the job done, even an iMac G3 from 2001 running Mac OS 9. But for this case, I highly recommend a 2012 unibody 13" (NON-Retina) MacBook Pro...
Although the photo shows it running iMovie HD 6, you can also use the QuickTime Player on Mac OS X 10.6 Snow Leopard or greater to capture the DV footage. Additionally, the 2012 unibody 13" MacBook Pro also has a Thunderbolt port and two USB 3.0 ports, allowing you to copy the files to very speedy external storage devices. Alternatively, if you feel like burning the footage to DVD in a creative manner, you can get iDVD (requires a MacOS version up to 10.14 Mojave to run) and burn the footage to disc using that, with the very elegant menus. (Of course you may want to edit the footage first; I'd recommend iMovie HD 6 or iMovie '11 if you're going to edit 4:3 DV footage and you want to add DVD chapter markers.
Heck, I've seen professional video digitizing services have older Macs from the late 2000s and early 2010s set up for the sole purpose of importing, editing and exporting such older video footage to disc with!