There is indeed nothing lost by asking the question, but by the same token there is nothing gained by someone saying, “yeah, it works for me”
One of the reasons a software vendor says they “don’t support” something is that it hasn’t done regression testing. This is possibly the case for E9 on Windows 11… E9 has been end-of-life for quite awhile now and Epicor just isn’t going to do a full test on such an old product. It might work for you. It might work for you for 6 months and then some new patch might break it entirely.
If you are unable to upgrade to a more current version, we’ll help as long as we can, but you’re kind of on your own.