Error 500 migrating from v4 to v5

OK… so what version of PHP should I be using exactly? I believe hillel told me 8.1 was required.
Here’s the post:

But 8.2 is untested? So that means for the latest version - v5.5.49 - I should be using precisely PHP 8.1, and 8.1 only?
it would be great to have a list of all the PHP extensions it requires also, preferably in an apt install command format : )
Since I’ll be rebuilding the VM anyway, it would be fantastic to have the full system requirements actually… How much RAM? How many CPUs? Any other details I should know?
Thanks : )