I would personally go Alpha 90 at those temps because I find Alpha 90 much warmer than P97 due to it having 2-3x the loft, but lower wind resistance so a wind shirt is key.
I use my P97 as a cold weather sleep layer more than active insulation, but either works well
I agree Kuiu makes nice products amd have many, but I’m slightly disenchanted with them for their direct to consumer model, but having ultra premium prices and rare sales. This comes off as greedy to me, so only recommend buying Kuiu when it’s 25-40% off which brings their prices within reason.