The Package Support Framework (PSF) was originally an open-source project to help Win32/DotNet applications run when inside an MSIX Container. TMurgent has taken up the support for the PSF in our own fork here on GitHub.
A new update to the PSF has been released. From the release notes:
- PsfRuntime: Fix in debug build when call to SetDllDirectory was
TMEditX is the licensed and more capable tool for fixing up MSIX packages since it doesn’t have to depend on the Microsoft MSIX Packaging Tool to create the final package. 
Last fall, Microsoft updated the end-of-life statements for Microsoft App-V with a date of April 2026. You can see the current statement at this link:
PsfTooling is the free tool to work in conjunction with the Microsoft MSIX Packaging Tool.