Alpine Quest handles OS just fine. I have the whole of Wales and most of the interesting bits of the RoUK at 1:25K on the SD card of my phone at all times. HOWEVER…. the only OS maps that work with it are the Memory Map QCT map files which were distributed to use on PC about 10-15 years ago so some of the road network is starting to get dated around big towns. If you can find someone with a copy of the .qct OS maps on a PC then it is just a small jump to having them on your phone and using AlpineQuest to view them.
I only ever record my rides on the OS basemaps as gpx files in AQ and then load them into strava on the PC at a later date.