It's not a bad time to start riding brevets, just the rules are a bit different than they were before covid. I managed to get a full series in last year (200,300,400,600) all ACP. Hopefully this summer will allow us to have official rides again. You can buy a medal if you finish an offical ACP brevet, and they can be used as qualifiers for the longer grand brevets and eventually PBP if that's something that interests you.
On brevets around here, they can be long solo rides since our numbers are sometimes very small. My first 400k only had 3 starters and we all rode different paces so I never saw the others again. My first 600k was similar but we kept meeting up at the controls. I would imagine Seattle has a lot more riders coming out for their rides in normal times. Some of my favourite brevet memories were the rides I did with a few others were we could work as a group and stop for sit-down meals. PBP was totally worth doing and I hope to go back... literally the highlight of the 2010s for me, lol.
Also I'd say if you like doing centuries then you'd probably enjoy 200k brevets at a minimum, and from there a 300k isn't really all that much more.