I know that Secure Boot in UEFI can be problematic for Linux. Are there new trix in UEFI for Win11 that need to be disabled?
I don't remember, and any info I might provide would certainly be stale.
IIRC, The same things that you have to do to get Win11 run on older machines is the same thing you have to do to achieve dual-boot. Now, I would install Win first, on it's own physical drive, then Mint on it's own physical drive, with the Mint drive as primary and dual boot out of grub in the final config.... Never got win11 to see the Linux drive.
I achieved that with win11 too, but the FUD at the time was that win11 will not accept updates in that state - I assumed that to be FUD, because it was updating fine running bandit on old processors. But the FUD was eternal (undenied) and I got itchy about that... And I hated living in Win11, so I eventually went back to Win10. I am still not sure if setting up a bandit win11 causes actual updating and security issues.
Full disclaimer: This is a Windows house btw. I love Linux - Particularly BSD/Ubuntu/Mint, but I have to stay up to date on the tech side, and that means Windows and MS Office I currently have no standing Linux installations, and only my two test bench boxes dual-boot... Both of those are Win10/Mint.