Here is my personal experience using both.
I am using Fire HD8+ (2020) and HD10+ (2021) tablets and a Samsung Galaxy Tab A7. There are definitely pros and cons to both and it comes down to how you plan to use the interface.
I cannot speak to native tablet features. I downloaded Fully Kiosk Browser (FKB) on all 3 and am using Sharptools as my dashboards.
The one benefit for me of the Fire Tablets is that you can use the built in Alexa app routines to show Ring cameras when Motion occurs. I have not been able to do this with my Samsung.
The HD10+ (2021) and Samsung Galaxy A7 (2020) are noticeably faster than the HD8+ (2020).
FKB is a dashboard app that adds a ton of customization. It has free (with watermarks) and paid options.
It has the ability to turn off screen in darkness, allow motion to wake the screen, select different start url (dashboard) for each tablet, auto reload start url after X time and much more.
FKB also allows you to add hyperlinks to almost any apps on the tablets (Ring, ecobee, harmony, etc.) Then in Sharptools you can create dashboard tiles that open those apps. You do have to side load google play on the Fire Tablets for certain apps. That being said, I find I don’t typically need to access those apps from my tablets.
Like I said before, I think it comes down to what platform you plan to run your dashboard from and how you want to use it.
Knowing what I know now and how I actually use my dashboards and if I hadn’t gotten such a good deal on the Samsung tablet, I would have returned it and bought another Fire tablet.
Hope that helps