Although I understand and appreciate the reduction in size, plus the switch to a 'native' toolkit, I think Popsticle looks out of place on most systems, due to being based on GTK, and it just doesnt adjust to the theme, plus it has no checksum verification on the usb side of things.
My personal favorite is Ventoy, and I see also value in developing an in-house solution.
Something that is integrated into the app, will always look and feel more natural.
I also have a new idea, regarding the feature set:
An installation to the disk, including GRUB/rEFInd, so the user can install Garuda without an USB stick.
This also avoids booting into UEFI and picking the right boot device in the first place.
I hope, you give this a fair chance of consideration.
This one doesn't even ship as an AppImage, so I'm not sure how I would implement it.
The thing is, I can make no assumptions about any software installed on any system. So how could I unzip the ventoy zip? How could I ensure the necessary libraries to open ventoy's gui installer are installed? How would I then proceed to detect the USB stick? Then I'd have to move the file into that directory, sync the filesystem, add various different error handling things for everything that could possibly go wrong, among other things. It's not like I didn't consider ventoy in the past >.>
If you can make it work, go ahead. Sorry, I just don't have the free time to spend so much time fixing something that isn't broken.