In my experience, support for Smart TV operating systems is shockingly short. After just a few years, they “age out” and the manufacturers no longer support the OS or the current versions of even the most popular streaming apps.
On the other hand, I have some pretty old Roku boxes, and they are working just fine and continue to get updates. Not only that, if they do eventually sundown the support, I can replace them for less than $100.00.