There is an account of autism built by autistic people, monotropism, developed by Dinah Murray, Wenn Lawson and Mike Lesser, which says something simple and clarifying: autistic attention is pulled strongly toward fewer things at a time, and held there more intensely.
Read that as what it is. It is not a description of a narrowness. It is a description of depth, and of unusually direct access to a state of absorption that most people spend years and considerable money trying to reach. People go on retreats for this. People take up meditation for a diluted version of it. You get there from a spreadsheet about trains, a guitar, a codebase, a horse, a map, a game.
And there is a decent chance you were shamed out of it. Told to develop normal hobbies. Had it removed as a punishment, or dangled as a reward for compliance in a therapy room, or simply learned to stop mentioning it after watching people's faces.
That was a theft, and you are allowed to take it back. Not as a coping mechanism, not as a reward for a productive week, but as one of the highest-quality pleasures available to a human being, to which you happen to hold an unusually short route.
Go and be absorbed in the thing. Lose the evening to it. That is not a relapse into childishness. It is the closest thing you have to coming home, and it has been waiting the entire time.