Definitely one of the most easily single player mmo’s I’ve ever played lmao.
You can pretty much play without ever talking to another player. The dungeons and duties are on a roulette system that encourages people to actually go through older dungeons, so you just get randomly paired with people whenever you queue.
Very little of it is a lot rarer, and more likely to find other players on a Japanese server though, and basically not solo-able unless you’re a vastly higher level than the content.
And that can be done through group finder and the wait is very short.
However if you're just into the story I'd recommend watching a YT video that cuts it together since the gameplay loop is really really boring
Shout-out to the Dan Floyd and his PlayFrame channel, where he's been doing a condensed playthrough of the game with just the MSQ, the interesting side-content, and highly cut segments of the interim gameplay. It's only near the end of Shadowbringers right now, but it's what got me into the game (as someone who was never into and mostly still isn't into MMOs).
I played the whole game solo. The big boss battles take in a lot of people, but you don’t really need to interact with them. Just watch what they do and do your best to keep up, help out, and not die.
Also, the few points others are talking about needing others, there's a group-finder and I'd say most people running those raids in group finder groups don't talk at all, so you can just pretend they're NPCs if you want.