Tundra has never had an awd transfer case with a center differential. Tundra has not had an OEM rear differential lock until the 3rd gen (MY22+). TRD OR is a very minimal upgrade. Cheap plastic fuel tank "skid" - really just a rock deflector, and basic bilstein shocks. IIRC they also usually came with 18" wheels instead of 20's in the higher trims that would otherwise come with 20" wheels. The only model that has any meaningful value IMO is the TRD Pro. The TRD Pro fox suspension is very good both on and off road. And it has significantly more rear suspension travel. IIRC it is about 3 inches more travel. Don't remember the difference up front. The TRD Pro rear leaf springs are also different - and TBH pretty damn cool engineering. The second leave has an extra end loop on it that functions as a skid plate of sorts for the front leaf mount bracket.
You can buy the TRD Pro shock set from Toyota for about $2800. Not cheap. But just an idea of what you're looking at for value if you're shopping TRD pro vs Limited or ??
It is possible to swap at least the early 2nd gens to the Sequoia/LC Aisin awd transfer case. Cost seems to run about $1k for a transfer case, ECU, dash light, and switch. I'm not sure if it's do-able on the 2014+ that switched to a BorgWarner transfer case. Everything is different on the 14+ and runs through the CANBUS so it's not a stand alone ECU for the BW transfer and that means that it's a lot more challenging to make the truck communicate with the transfer case if you were to swap to the Aisin AWD unit. This is all second hand info. I have not spent any time looking at electronics of them to see if there's an obvious solution (to someone with a lot of electrical component background). It won't be plug and play. Most systems however are simple enough that we could come up with a simple intermediate circuit board controller to interface between them. It's just a matter of having time to figure out and design one.
Also - ATRAC is not switchable and is automatic in 4lo. ATRAC on the tundra is very weak compared to all other Toyotas I've owned. It's the opposite of aggressive. Don't expect it to work nearly as well as your LC. My 5th gen 4Runner was night and day better than the Tundra is. If I were going to work on an electronic mod for the Tundra - this would be at the top of my list. I'd love to figure out how to add ATRAC and MTS/Crawl from the LC200 to the gen2 tundra.