If they can’t I’d either recommend to use Linux or buy a new computer. I wouldn’t want to support “unsupported” installation of Windows 11 on “older” hardware, even if it worked perfectly fine as of now, since that would be asking for problems later.
It’s better for them to upgrade to windows 11 than stay on unsecure OS.
And of they can’t due to the TPM requirement?
If they can’t I’d either recommend to use Linux or buy a new computer. I wouldn’t want to support “unsupported” installation of Windows 11 on “older” hardware, even if it worked perfectly fine as of now, since that would be asking for problems later.