Windows 11 on Intel Mac?

Intel or M1 - you mention both and they are very, very different architectures.

Windows 11 has very strict hardware requirements related to secure boot and TPM 2.0 and slightly less strict ones about amount of RAM and supported CPUs. Any Intel Mac that meets the requirements should support Windows 11 - although I can't recall if any actually meet them. And, given Boot Camp requirements, you would need to install Windows 10 via Boot Camp and then upgrade to Windows 11 from inside Windows.

On M1 Macs, Windows 11 ARM in a VM is the only option.

Back in October 2021, I did manage to install Windows 11 on a 2017 iMac 18,3 using Bootcamp, but I can't recommend it. I followed one of the suggestions in the thread on this forum entitled "Can I install Windows 11 on my iMac 2017" headed "Official upgrade method to Windows 11". The problem is that all of those suggestions amount to a hack that circumvents the inbuilt security requirements of the installation, either by modifying the installer, or by editing the registry with regedit. It worked for a few months but then stopped updating. I fled to Parallels, but importing the existing Bootcamp resulted in a number of problems, and a clean Windows 11 install proved necessary. The "vintage" iMac is now on the current 24H2 with no further problems. Parallels sets up a virtual hardware environment that is fully compliant. In retrospect, I suggest that Secure Boot and TPM 2 are worth having and that it is not a good idea to try to do without them.

In Parallels you can instantiate a virtualized TPM chip even though none exists on the iMac hardware (the encryption key is stored in Keychain - which can make moving the VM to another computer a pain in the posterior).

https://kb.parallels.com/122702

Disk space is really usage dependent, although I'd personally say at least 64 GB if you plan to download any programs and store a moderate number of documents - more if you sync a lot of stuff via OneDrive, of course.

RAM - probably minimum 8GB for the VM, but I think Parallels 18 and later has an automatic mode that can dynamically allocate the necessary RAM for general use (and also the GPU VRAM assignment). So you can probably leave it on "automatic" and not think about it.

What info are you looking for/missing? Happy to try and find some additional detail. Windows 11 Intel system requirements are here: https://support.microsoft.com/en-us/windows/windows-11-system-requirements-86c11283-ea52-4782-9efd-7674389a7ba3.

The need to install Windows 10 and then upgrade is due to Boot Camps own requirements given how it downloads and prepares a Windows USB installer and the USB with the additional drivers - all Windows 10.

Windows 11 ARM in VM only is because (unless something has changed) the only ARM architecture Windows supports natively is SnapDragon - but I'd need to track down additional details.

So is the T-2 chip sufficient to offer the secure boot & TPM 2.0 architecture?

I guess the answer is No.

Is basically leaving your T-2 chip unsecured going to stop any installation of Windows 11 from taking place?

I guess the answer is Yes.

I should have specified that the Bootcamp installation was done from within Windows 10. It was a matter of removing from the installer the component that checks the hardware. or of editing the registry to circumvent the hardware check. So far as I am aware, Apple hardware is unable to provide Secure Boot and TPM 2.0 in the form that the Windows installer expects. So this rules out Bootcamp. The Parallels VM provides its own "hardware".