AFAIK, you need to use seperate drives and install the OSes in such a way that each drive has its own EFI partition. (Installing with the other drive disconnected is the easy way.) Then only use your UEFI boot selection menu to choose which drive to boot from.

https://github.com/Bladez1992/LTSConvert

Privatize the profits (stocks for investors) and socialize the losses (bailouts with taxpayers’ money)

Future headline: Intel, under new management, to now only manufacture motherboards with locked Microsoft bootloaders