Because Bluetooth is sooooo slow yawn
Edit: And I already tried OTG. Its slow as fuck because of the USB 2.0 bottleneck makes it take 3 hours whereas Quickshare would’ve taken like, idk maybe 15 minutes or less. Ironically wireless is faster, but I also need it to work for non-certified / custom roms.
So the way hotspots work, is if you want to transfer (without going through the internet) files between device A and device B, you need a device C to host the hotspot, then have A, B connect to it. If you use A to host the hotspot, then B connects to A’s hotspot, A still wouldn’t be “on the same local network” as B. Its weird.
Well, what we mean by “on the same network” maybe more complicated then it sounds if a device has multiple network interfaces and a non-trivial routing such as any modern smartphone that smartly switches between wifi and cell. It’s plausible that various apps and devices have a different behaviour which network they treat as local/standard.
However, I just tried it out with two Samsung Androids. One is a hotspot and has no other wifi. The other one uses the hotspot (and no other wifi obviously). Then lauching pairdrop, they can “see each other” (through broadcast packages I assume) on the local network. During testing the hotspot device had internet access through 5G, so both devices could reach paridrop.net, but I believe, this is not needed while in local network mode. At least the file transfer itself should not go through the internet in this mode.
I had similar a similar experience with syncthing. Sure, the hotspot is a hack and neither super reliable nor super fast on most phones, but at least my phone does not seem to block access from/to the hotspot device.