Right click “open with”

Im finishing an application that has a custom context menu. ATM I have “open” and “open containing folder” working. I can’t seem to get a “open with” that seems to be so common with file explorers. I’m using Linuxmint 20 and I’d like this option available.
The problem is of course depending on the file type there would be different options for “open with”- so I don’t think we’re talking about predefined lists of options, but rather something extracted from the host OS.
The context menu part is fine. Just any help with the “open with” would be greatly appreciated.