So the AeroGlass for Win8+ would violate the EULA, as the restriction or limitation in this case would be the inability to display Vista/7-style glass. Also there was undoubtedly some disassembly and reverse engineering of internal DWM functions to make it work. And I think this goes for Stardock's assortment of desktop enhancement products as well, but they may have the resources to perform clean-room RE. This also goes for products that may have also violated EULA in this way, such as VMware (which reimplements some kernel mode functions for systems lacking them) and Chromium (which uses undocumented classes of some Native API functions).
But these EULA terms are often superseded by exemptions in copyright law. In Canada, we have section 30.6 in the Copyright Act where:
(i) would cover the additions to the Vista kernel that make newer drivers run, such as NVIDIA 398.11. Perhaps adding support for newer user mode software also plays a role in "compatibility". Adding support for NVIDIA 398.11 made Windows Vista compatible with a system with a GTX 1080 Ti, then the extended kernel also made new browsers and games compatible; thus, it is now fully compatible with the particular computer, whereas it was not when it could not run the software and device drivers.
(ii) would be technically satisfied if the process of installing the extended kernel constituted the adaption or modification of the software, to create the reproduction (Vista with extended kernel installed). I believe this is also valid.
I expect most of the world to have similar exemptions, including the EU where MSFN is based.
An activation bypass would not usually be essential for compatibility, unless the activation procedure itself made it incompatible. This is not the case with any form of Microsoft Windows.