- Install latest Ubuntu to thumbdrive via unetbootin or etcher (now balena bs or whatever)
- Install refind after disabling the software integrity lock bs
- Create new FAT32 partition like 200GB if you can spare it on a 1TB Mac OS if not, you need at least 20GB
- Boot to live Ubuntu GUI install using compability mode (it will fail otherwise)
These instructions work: https://github.com/cilynx/rtl88x2bu to achieve 200MB down and up if within LOS