Re: only 40% of the aew roster have been revealed so far
Signing could be to non-exclusive deals. AEW is running two shows a week, with the idea if you work one you probably won't work the other. So there is a lot of time for their talent to work elsewhere if they choose.
Could be US/Canada exclusive, no US television/stream, AEW right to first refusal on dates type contracts. This could be their "developmental" of sorts - scout indie talent that might not be ready yet and sign them to modest money deals that gives them enough to be able to wrestle full time largely while staying in the indies, but used on AEW television on occasion to also increase their name brand to charge more on the indies.
Now for this type of contract to work AEW would need to have a right to match stipulation whereby at the end of this type of deal they could retain the wrestler on a full time deal rather than being poached into NXT.