After doing some research, it seems the modern way of approaching this is to get a Thunderbolt dock for laptops. It has to be Thunderbolt and not just standard USB-C, even though they both use the same form factor.

I found this as one of the cheapest options at $140: https://www.amazon.com/dp/B0FQ7VXYDJ

You would then get a Thunderbolt to FireWire cable, which is a simple cable and less than $10.

The problem is that FireWire is incredibly picky about power delivery and so anything that officially supports FireWire also has to have a really antiquated specific power delivery spec that no one is streamlining anymore. So it’s unfortunately niche at this point.

But a lot better than $4k!