Exactly. It's a matter of scale as well. The "No eat... only focus" isn't "Oh hey, I was having so much fun I'm having lunch an hour late". It's more like "I'm not sure I was even having fun, I was just FOCUSED. Now it's multiple hours past the time to eat, I'm in strong physical pain due to intense hunger and feel off balance/sick from the tanked blood sugar."

How often, how extreme, how much of it is a concious choice vs something you can't stop even if you are aware it's happening.

Much like other neurodivergences. Most symptoms will be stuff that even neurotypicals experience occasionally, which leads to "I feel sad sometimes too. Have you just tried being happy?".