Thanks to Erik and Nick for the replies.
Erik: my iPad Pro is 1 TB, so it has more storage than any cloud account I want to pay for. I will use the cloud for showcasing and portfolios, but not for total photo file keeping.
Nick: my MacBook Pro died and I bought this new iPad Pro as a laptop replacement. I am aware that some simplifying is part of the deal, and that’s okay, hence I will give One Big Folder a try and see how it goes with the ‘smart’ tagging and catalogs/albums and search ability of Apple Photos, along with RP for raw editing and Affinity Photo for layer work. My big concern now is what do I do when the iPad fills up (and how to delay that point by not dupli-triplicating all my photos on the iPad any more than I have to.
I admit that I listened to the talk about iPadOS having file management and external drive access, and made a big mistake thinking that meant more freedom for where my photos can reside and be available to apps, than seems to be the case, at least as of today.
So I am learning the hard way, and I am in up to my neck now, so there’s no going back and I just want to make the best I can of the situation. I do need some help with advice from those more familiar with the limitations and abilities of the various apps, and I really appreciate the support I am getting.