Indeed my Android phone sees my Linux PC. And the PC can send a file to the phone. At first the file transfer to the PC didn't work and the icons just twitched. After 5 minutes it works now strangely enough.

Edit: so that was SnapDrop.net this is so confusing now. Are you the author of that GitHub repo?

I used Snapdrop before they got bought and found it pretty reliable. It sometimes would not transfer and I went exploring.

I used magic-wormhole-based Warp and liked it, but now I use croc of getcroc.com for almost everything. Whether it's sending files to myself or others, it's just the most flexible and seems to be reliable and fast from my use.

(I haven't been using it super long, but I heartily recommend.)