I've been on 115.10.1 for a while and it's not offering this update. Since updates are now via ESR, is it safe to assume that I have to actually download this version and install it over my current version?
115.10.2 should be available to the general public tomorrow (03/05/2024).
The next major release will be TB 128 and it will probably be available in the next couple of months.
You have to download “ViVeTool: an open-source command-line tool to enable experimental but hidden features on your Windows computer”.
https://www.makeuseof.com/vivetool-windows-guide/