You can run Win11 on older Surface Pro devices by adding a single registry key at Computer\HKEY_LOCAL_MACHINE\SYSTEM\Setup\MoSetup. Add a DWORD 32-bit key called AllowUpgradesWithUnsupportedTPMOrCPU and set it to 1. See this article for more details: https://www.pcguide.com/windows-11/how-to/allowupgradeswithunsupportedtpmorcpu/
I also upgraded the TPM1.2 on my Surface Pro 3 (2015) to TPM 2.0 so the only limiting factor remaining was my i7-4650U CPU. The firmware update installer and instructions are here: https://support.microsoft.com/en-us/topic/install-and-use-the-surface-pro-3-trusted-platform-module-tpm-update-tool-d5e52c61-c7ec-0544-b6e9-e0e0b85cbc10
Here's proof that a Surface Pro 3 can run Win11 :)