What is going on with VSIX extensions?

Lots and lots of ground to cover before the thread title is covered. Not sure where to start anymore. This post has been building up for months, since I first installed VS 2022 Community Edition. I previously thought I posted to an MSDN subset for VS2022 but that turned out to not be a forum post or even a support request but a feature suggestion.

VS 2022 is "incompatible" with absolutely every existing VS Addon for any prior version and that includes the VSIX-style addon supposedly created by a Microsoft employee of some sort. That came part-and-parcel with VS 2022 totally obliterating COM Interop? Or not??? I can't find documentation anywhere that says anything but that VS 2022 is totally incompatible with anything but VSIX, but then in reality VS 2022 is totally incompatible with anything but "VSIX Created With VS2022."

At the same time, the template for VSIX is badly broken or else (I strongly suspect) it's VS2022 breaking things at runtime, and nothing wrong with the file on disk. The problems created range from bad class-naming in autogenerated code to a grotesquely broken NuGet pre-configuration which has to be surgically corrected with individual uninstalls and reinstalls with at least 1 full VS restart between each individual action.

So I'm at the point where the 1 thing I desperately want and need is File Nesting, but no existing VSIX addon works at all and trying to create a VSIX addon is just a nightmare from actual Hell.

I downloaded the source of what SHOULD work from https://github.com/madskristensen/FileNesting/tree/master and opened it up in VS2022. Most of the references in that project are "offline" references -- some of them are higher versions than VS2022 says NuGet has -- yet for some unknown reason VS2022 spits out globs of nonsense errors about how the same class name exists in 2 different namespaces when only 1 of those namespaces is relevant for its using statement... and those nonsense errors disappear altogether if I uninstall the NuGet packages that exist and reinstall the "latest stable version." There are dozens of these with an unpredictable web of dependencies, and NuGet is not exactly "easy to use" when it comes to uninstalling a bunch of stuff without deleting the whole project and starting fresh.

I am currently in the process of surgically removing and reinstalling NuGet packages, because very evidently VS2022 is only compatible with VSIX extensions built on VS2022 and over a few weeks of trying to work with it, what I'm coming to grasp is that VS2022 may be totally incapable of producing a VSIX extension.

This post was originally put on MS Q&A and somebody gave me a link to this forum instead. Since I originally posted, I did successfully re-reference and build the mentioned extension and I gave that dev a pull request for the VS2022 compatible project. I think the problems encountered should still be documented where people can find it when they encounter the same.