Does the LTSC have all the features needed for mainstream programs and games?
Yes. The one place you may run into issues is with Microsoft-specific services, for example I'm not sure if Gamepass works.
But if you're just using Steam (or any other third party storefront) you won't have any problems at all.
By Microsoft's own admission, it sounds like it:
> Windows 11 IoT Enterprise LTSC is built on the Windows 10 / 11 code base so it’s natively compatible with the software and solutions you use today.
https://www.microsoft.com/en-us/evalcenter/download-windows-...
I've not tried to use it specifically, which is why I'm curious.