I am OW Emerald via AA EXP. I recently booked an economy intra-Europe flight on AB. I called the US line, selected the business class option, and had no problem getting my preferred seats assigned. The agent offered me 1F without a fuss.
We'll see how other upcoming intra-Europe flights go. I have one that I booked before AB joined OW, traveling on the same PNR with a non-status passenger, and I'm not sure what to expect.