I use headphones mainly for noise cancellation so therefore my vote goes to Bose QC 35 II. Additionally, I use it as ear cover if co-working AC gets too cold.
You can search Angellist for remote and internships I think.
I'm not sure about a site dedicated to this, but as @aviaryan mentioned you can search on regular job boards and use the right filters.
Having said that, I would advise against doing a remote internship. The beauty of an internship is that you get a chance to work with more experienced people and see what it's like to work at a company. I think by doing this remotely you lose out on much of that.
This isn't about all web services/apps but if you are making an app that people will use 24x7 (figuratively), I prefer native in that case. An example of this would be Notion, a note-taking app. I tend to keep the note-taking app open at all times so having a webview running for it takes a toll on laptop's battery and performance which I don't like.