Why do you see him as an OG since his draft profiles and scouting reports all see him him as a pure LT?
His physical metrics are typical of an OG at this level. They said the same thing about Jackson coming out of college. Jackson actually played better at RG than LT. That is not to say Jackson won't develop into a very good OT which I think he will. Collegiate OTs are often smaller with less play radius than the typical NFL OTs.
I project Thomas to be worked primarily inside by Carberry. Remember Rams like to convert college OTs into OGs because they normally have better arm length and feet than collegiate OGs. I think Thomas primarily will become an OG with the ability to kick outside to OT particularly at RT if needed.
Thomas was a 6th round pick which is exactly where Snead likes to grab his backup OL. But it also means, he showed more potential than the average UDFA OL. Thomas' forte is in run blocking primarily in a zone scheme. He's got good mobility to pull in a gap scheme but he needs a lot of coaching up to do that. Blocking on the second level is something many OL struggle at. But with Zackary's speed, he has the potential to become good at it.
The fact he has been on a PS this season means he's been getting coaching, practice reps, and training all season. He simply needs to learn the Ram's playbook and he should be available sooner. It's why I assumed they would mine the PS players of other teams for OL. I wouldn't be surprised if he ends up ahead of Skura and Aboushi on the depth chart this season. That's how much I like his potential. Both Skura and Aboushi are marginal players IMO.
Since the Rams are down to only 6 healthy OL this week I see Thomas as giving them much needed depth at both OG & OT this week.