A docker container is a way to easily install software on a server without having to install dependencies yourself.

A VPN (Virtual Private Network) is a way of securely connecting to your home network without exposing it to the world.

FLAC and Opus are audio formats. FLAC uses lossless compression and offers the best uncompressed quality while not being as huge as a broadcast wave (.wav) file. Opus is similar to an mp3, that means it is a lossy compression, but it sounds extremely good at small bit rates/with bad connections. The transcoding-on-the-fly-bit means the user opens up the private Navidrome website running in their home from the road and the Audio they play is compressed and sent over on the fly as they play it.

Self hosting sounds scary, but it is an essential skill nowadays and extremely useful. Things I self-host (besides websites) include a partskeeper instance which is essentially a stock keeping system for electronics parts, jellyfin as a netflix replacement for films and series, my mailserver (mailcow), paperless-ngx (hooked up to a scanner, allows automatic text-recognition and tagging of invoices, letters, etc.) and homeassistant (smart home).

That probably makes it appear like I have to spend all my free time on this, but it takes surprisingly little of my time to maintain this, with a lot of it running on a single Raspberry Pi.

It has always been clear that people who are scared of performing a few google searches wont use these services.

I'm curious how you came to find your self on Hacker News without either a passing knowledge of some of the things mentioned above or an innate curiousity to learn about the rest.

Self-hosting has its price, one of which is knowing what you are doing. Just keep using Spotify, there is nothing wrong with that.