please also note that the version of "WebView2Loader.dll" which is in use is very crucial. I had almost the same problem with "Microsoft.WebView2.FixedVersionRuntime.101.0.1210.39.x64" when I tried to use the WebView2 component in the MMC Snap-Ins with types of "HTMLView" or "FormView".
I just copied the abovementioned dll file (version 1.0.1248.0, size=157640 bytes) in a proper path that was accessible for the project (you could just put it beside your project output files first to test it) and then WebView2 browser started to function as expected. Microsoft error messages sometimes (at least in my case) was a little bit misleading and did not convey enough and to the point information.
I received "BadImageFormatException" that normally occurs when you mix platform targets (for example using a dll file compiled in X64 in an application that targeted for x86 or vice versa) or mix native code and .NET but that was not my problem at all. I hope this help one who may stuck in.