I had what i assume was the same issue the launcher crashed when i attempted to launch from steam, and executing bannerlord.exe directly didn't work either. when i attempted to use crashuploader.publish.exe in the crashuploader.publish directory it opened a webpge to download the 4.8 .net framework.
Downloads for building and running applications with .NET Framework 4.8 . Get web installer, offline installer, and language pack downloads for .NET Framework.
dotnet.microsoft.com
after doing so the game seems to be working normally though i've barely started playing.