I went the /e/os way and quickly turned back. Not to dismiss the effort of the maintainers, but it really felt like a frontend on lineage os meant to sell alternative cloud services. I did not find convincing arguments over a bare lineage os and the pretty much forced /e/ cloud was a total turn off.

I went the "real" security / privacy way and switched to grapheneos. Very happy overall, already went thought with 2 major os updates, no issues whatsoever. Only issue would be if you want Google pay (won't work on graphene). You'd need a pixel phone if that's in your budget. The pixel phones are great at photos, but pretty "meh" otherwise

for the first point, Transmission has a pretty serviceable web client that works great on iOS as a web shortcut

its just occurred to me you might mean downloading torrents directly to you iphone, rather than a remote to some other device.... in that case a web client isn't sufficient, you'd have to sideload

You can actually (indirectly) torrent on iOS via seed box. I use SonicBit, which has an iOS app. I find it’s actually more convenient than torrenting directly as the files are stored and seeded online yet still accessible to me when I need them. Then you can download the files to your iPhone/iPad.

On the price side Apple is bringing out a new SE in 2025. Should be cheap. The First issue I don’t know about so can’t respond (torrenting).