an iPad with cell service (so I could get the built in GPS). I also use an old (2012) Samsung Galaxy Tab running the original Back Country Navigator software. The Galaxy Tab is so old I can’t update it, and it’s only good to use as a stand alone GPS device now, so it hardly ever gets used.
Bruce, I think you are overthinking this problem. Since you want an Android based tablet, ALL of the major brands have off line GPS tracking capabilities if used with the correct app (ie GAIA, Onx-Off-road, OB1, CalTopo, just to name a few). The question you need to ask is what size of Tablet you want to use, what other features do you want, and what is your budget.
IMHO there are really only two brands of Tablets I would put my money on. Samsung and Apple. Samsung has been killing the tablet and cell phone market for the past 20 years with their Galaxy series, while Apple has been leading the way in technology advances in mobile hardware.