I honestly don’t really remember the main quest progression (I last did it a really long time ago), but I think there were a couple of steps that were time or exploration/research gated…
I can say that the story of Artemis has an ending, you should probably just try go on and research some Archive related things on the Base computer or jump around to new systems
As a general rule, IMHO, to really enjoy it you should treat NMS as a sandbox game that happens to have a story that sometimes pops up
Some Nexus missions are targeted to groups, which makes them tedious to do alone, just for the sheer amount of things to kill/retrieve etc
Aside from that - which is honestly a small optional part of the game - you can disable the multiplayer from the Network options and never think about it