@GalTabS3, you don’t have to be a nerd to realize very quickly when comparing the specs of the SM-T310 and SM-T825 that both tablets have nothing in common.
The Galaxy Tab S3 (SM-T825) is clearly the more potent and still a premium tablet: fast, thin (only 0.24 in), 9.7" Super AMOLED display 1535 x 2048 pixels, USB Type-C 3.1, magnetic connector up to stock Android 9.0 (Pie).
You can find some UNOFFICAL custom ROMs + TWRP recovery builds for your Tab S3 “gts3llte” on the Internet. But my clear recommendation is: Get a /e/OS-Q GSI version 1.1 installed, based on AOSP 10.0, and your Tab S3 will climb new Android spheres with access to the /e/ ecosystem ( Murena Cloud, App Lounge², Advanced Privacy³ ) and will be much better equipped than with Google Samsung Stock Android 9.0.
²³Sorry, new users can only put two links in a post.