Suggestion: make .desktop files work for portable apps (relative paths, launching)

I discovered that .desktop files are really nice for desktop apps. Many environments will do extra things for .desktop apps like if even just associating a logo, but sometimes also extra recognition as a standalone graphical app over who-knows-what-background-tool that can be favorited and added to launchers etc. Also, a .desktop file avoids the issue where an ELF binary is recognized as an ELF library accidentally and can't be launched directly. In overall it seems like a really useful file with nicely standardized meta info identifying something clearly as a desktop program, and it's a cool useful standard that seems like worth adopting.

But I've hit a roadblock though since I tend to offer my (fully free/open source) apps prebuilt as portables:

I noticed that 1. .desktop files don't allow relative paths for e.g. the file to be executed, and 2. many desktop environments don't allow right-click -> run on a .desktop file. These two things are the major blocker for portable apps throwing in a .desktop file that "just works." (@ "portable apps": those that e.g. use AppImage to work around the need for separate .rpm/.deb files and want a simpler, leaner distribution than via flatpak)

Wouldn't it be nicer if this standard was also used by portable apps and without complicating things like e.g. now suddenly needing an install? I think it'd be really great for the ecosystem as a whole if this "in place" use worked such that portable apps can jump onto the .desktop train. I do recognize some of the attention is moving to flatpak as a distribution model, but I think especially for power users and devs directly-run portable apps won't go away so it would be cool if this allowed .desktop files use.