Here's my take on it and note I am comparing it to my N7 deb. I can't say I agree with everything the OP here has to say.
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A couple days ago I received a Samsung Galaxy Tab A 8.0" with S Pen (2019) SM-P205 LTE which is unlocked for GSM and locked for CDMA (Verizon/Sprint). It's an international model, so there's no warranty in the US but I knew that going in.
I have been running a the AICP 14 pie custom rom on my Nexus 7 2013 deb for months now, updating it each month about a week or two after the security update hits. This runs exceptionally well on my Nexus 7. It runs at least as well as the factory install and battery life with a few mods is great.
The Samsung runs 9/pie and appears to have about the same screen resolution as the Nexus 7. It's not what I'd call much faster than the Nexus, but is a little snappier. It's almost the same size, just slightly wider. I can't say I like all the boatware they install, but it is what it is. One thing I definitely don't like is after updating it, they still are at the May security update. It's nearly October so to me this shows Samsung doesn't make security a priority. Another con is battery life, it's substantially poorer than my Nexus 7 and granted running pie it might improve over time but I don't feel it will. There's few options for optimizing battery usage like I have on the Nexus running AICP. Wifi on the Samsung is excellent much better than the Nexus 7. I have not installed a sim so haven't tested the modem. It can of course make emergency calls. I also have not tried the s pen but am looking forward to playing with it some.
Final thoughts on the Samsung as a Nexus 7 2013 replacement... IMO it's more like a direct replacement than an upgrade and if my Nexus died then I'd certainly replace it with the Samsung tablet as my daily driver, either wifi or lte. The Samsung LTE version only costs marginally more than the wifi only version so I went LTE. I've heard that modding the Samsung devices can be difficult, but for me I use my pad for email and reading so I really don't care about mods or custom rom for it. I only got into custom roms for the Nexus 7 due to it being so far out of support and the fact that it was still working well.
jb