Either
a) setup a dual boot Win 10 or Win 11 23H2 version
or
b) just lock you present Win 11 version to 23H2.
You can fudge this by editing registery files or go down the route of upgrading your Win 11 instalation from Home to Pro. The Pro edition is designed for businesses and has the built-in feature choice of locking the installed Windows version to whatever you like to avoid automatic version upgrades breaking a business-critical system. This is exactly what is happening to us. Win 11 Pro keys can be bought cheap from one of the sites of dubious reputation for less than 2 quid. The 'dodgy' keys work or they will give you another one. There may be a difference between a fresh install key and an update from Home to Pro key but not 100% sure. Some people say the keys are from stolen credit card numbers but I don't know how true this is, selling for less than 2 quid, it sounds like a lot of work. I believe Steam support ends Nov 2026 and that may be it for the G2, but that's still another 22 months.
The lock to W11 23H2 means you still get all the security updates so no problems there.