I have to think that it would be pretty hard to fool a TPM "user". But there are physical TPM modules and TPM that are executed in firmware, or an fTPM, like AMD and Intel do with CPU's and UEFI since 2017 or so. I've even read there is a software TPM2.0, but no clue as to whether Win11 install will accept it. But it seems to me it would be useless if using BitLocker since you have to decrypt the drive very early (TPM stores the keys for decryption) to start the OS so it can run the software.
If you're concerned that your system isn't going to get Win11 because it's hasn't got either a hardware TPM or firmware TPM 2.0 I wouldn't let it bother you. First is that if it's that old then it will probably not comply on any of several other hardware requirements that are pretty strict. Get the PC Health Check app to find out, and keep it updated because MS has stated they're re-evaluating things.
But also: Win10 will be around and supported for a while yet. Considering what I've seen of Win11 it's nothing to get excited about and I'm glad Win10 will be around. I just see frustration as things I used to always find quickly I now have to search for. Unless I see some under-the-skin changes that are compelling....way more compelling than the UI changes we're seeing now.... I may stay with Win10 for awhile. I can enable SecureBoot, TPM and hardware virtualization on Win10; I don't need a forced OS "side-grade" to force me to if that's all it's doing for enhanced security.