My opinion for spring allium planting in the PNW is to get them out when you can, even if they are a bit on the small side which I think yours are. If you can get soil worked up thats not soggy and you don't lose the slow growing seedlings in the weeds, go for it!
That said, keep in mind that they may grow faster in their pots in the greenhouse or wherever you have them now. Just get them in the ground before they get root-bound.

I'm also hoping to transplant a few beds of onions this week.

I've grown Ambition and its sister varieties, but I wait until they have that third strong upright leaf before setting them out. By then they are at least 8 weeks old and I've trimmed them back to 4-5 inches several times. I set out my seedlings this week but I'll use a tunnel to keep them happy for the next bit of topsy turvy weather.