The dev did sanction the NZBGet fork tho (nzbgetcom/nzbget). So there is still a viable and actively developed NZBGet application for those who want it

For me, Usenet has replaced public trackers and competes with the private trackers I'm on. I find I'm mostly going to Usenet anymore and am only going to PTs if the release they have is higher quality or to keep my activity levels up, but most of the PT releases get uploaded to Usenet anyways. Occasionally there's some obscure thing I can only find on a PT, but it's rare. Getting a few good indexers will definitely increase your coverage.

You can preview the indexer only, just wouldn't be able to download anything without having a provider and a download client (like SABnzb or NZBGet). I think the provider usenet.farm has 10GB free trials or something like that if you did want to test it out.

I use Sonarr and the manual search available on the Indexer sites, which suits my needs. Haven't tested out any other searches.

But happy to answer any other questions you have. Feel free to DM me.

1. Only some PT's are interested in your IP address and, from my understanding, those that require it mostly do so for account creation tracking. That way, if you get banned it's harder for you to sign back up since your home IP will be blocked. But most (if not all) PTs still allow you to run your torrent client over a VPN with no issues. And only a small few won't let you access the site from a VPN (some just require you clear it with staff first).

2. There are ratioless trackers where you just have to keep the torrent seeding for a minimum period of time to avoid getting a H&R. Usenet is great. Haven't played around with Realdebrid.

3. There are elearning PTs but I'm not on any of them to know how the content is. General trackers like IPT and TL also have educational sections, but again, not sure what the level of content is. Usenet can probably fill a good amount of what you're after though. I'd recommend signing up for the NZBGeek 3day trial just to look through a catalog of what's out there. That should give you a decent idea if Usenet is worth pursuing.