There're some external GPU enclosures with Mac-Compatible Nvidia cards that connect via USB-3. None of that is officially supported, and it is expensive, but based on cursory searches I did, it seems to work for people. It's still expensive and can only be used when you're at a desk, but those are imho fair compromises.

Now, I'd love for Apple to release an official external GPU (like Blazer did with the Blazer Stealth) but I highly doubt they'd do it.

https://bizon-tech.com/us/bizonbox2s-egpu.html/