Hey @frikkr that wierd glossy spot was something that I missed in my mask. I went back and fixed it but I guess I didn't give it enough time to calculate the roughness value before exporting it. Good catch btw lol.
I do a couple of thing to hide seams, first is i'll paint over my seams to blend them, the interior of the mouth was done that way. I also sometimes hide seams with height info. I actually removed the head, the back legs and front arms the inside of the mouth, and the claws teeth and eyes are all seperate as well. I unwrapped everything then combined it so I only had to deal with a single uv map in painter.
I also try to make sure I plan my seams out ahead of time too, like hiding them underneath, or on the inside of limbs where people scrutinize least often. I split the dinosaur underneath right up the middle. If you zoom in super tight you'll see the line. Its not as apparent on the belly because I blended a second material over top of the base one.
Padding is also king, I add it in painter and I make sure I have enough space between islands as well.