IIRC that’s not accurate. You only need that “pro feature” if you want to be able to apply activate kernel updates without rebooting. Unless you have that requirement and an armada of devices matching that profile you don’t need to pay anything.

Testing a normal Linux installation sounds like a good idea. In my opinion it’s better to transition to Linux than switch. That way you can go back to your previous system setup and see what you are missing or need without having to open your computer and swap hardware. If you can add the old or new SSD as an external drive and so that you can can boot then your plan might work out.