To change your default file manager in Windows 11, open the Start menu, type the name of the third-party file explorer you installed, and select "Open File Location." ...

To change default hard drive from C: to D: in Windows 11/10, change the default save location for apps and files, move user ...

If you're done with File Explorer in Windows 11, you can hack the Windows Registry to change it to something else.

OpenOffice is a productivity suite that's similar to Microsoft 365 (AKA Microsoft Office). You can set its apps to open files by default.