Any learning activity pertaining to the domains of your certification(s) can be used to earn group A CPEs.
If they don't provide certificates of completion, just keep your own records / notes that are good enough to prove you've undertaken the learning activities if faced with an audit - I'm sure a platform like that likely keeps track of your course progress whether they provide certificates or not.
In Pluralsight they keep track of your activities and it shows what you did, how long it took and on what date you did it. Basically all you need as evidence.
I assume (and I know I shouldn't) that something similar is available in O'Reilly.