I like Dexter a lot, but even though he has a similar body type to Deforest Buckner he doesnt have a similar skillset or playstyle. I'm going to sandwich his negatives between positives to avoid a pessimistic tone here.
Gervon is big, strong, fairly athletic, gives good effort and doesnt really take risks with his assignment. However, he's big but with only average length - hes not able to control bigger OL without them getting both hands on his pads and he can at times play too high which loses the leverage battle. He's also not a particularly good handfighter which would be a real helpful skill for him to develop.
He's strong but not particularly stout, he gets really good push on his bullrush but he does get moved in the rungame when linemen get inside him/on his pads or especially when facing duos and while he can stack linemen well he doesnt consistently shed them as well as he probably wants.
He's fairly athletic but not explosive, he can pursue runs laterally fairly well even with a stacked OG/OT in his hands but he rarely beats his man to his gap with speed. This is kind of compounded by his notorious issues with his first step/get off on the snap that he had coming in to the league.
He gives good consistent effort on most plays but doesnt really have a high motor, to me he seems like a guy you rarely see give poor effort but hes not someone flying around the field play after play.
He doesn't take risks with his assignments but this also comes at the cost of him often being reactive vs. proactive in his play - he clearly prefers to read and react to runs versus predicting and penetrating, I dont know if thats a football IQ thing or just someone who needs to "look before he leaps" before choosing how to play a given snap.
I think the above limits his ceiling as a traditional 3T. I do kind of suspect he may have been a better 4i or 5T in an odd front where some of his deficiencies would be less relevant or even hidden and his strengths would play more to what he is asked to do.
Still, he's been fairly productive DT with his pass rush, his bull rush is good and he has the savvy to take advantage of stunts and gains on the line to get sacks. I think he pushes the pocket very well, he really tests OLs anchor which is less useful when he goes up against Gs but is a PITA for OTs and Cs that get asked to handle him alone. I think the best thing the Bears can do at DT to help the run game is get a 2nd stout DT they can play next to Billings on 3rd &2/4th &1 - Byron Cowart is not that guy, and I dont think Dexter will develop into a good run stopper either. Still, the NFL does value DTs who are good pass rushers even if their talents against the run amount to being "just a guy." So dont throw out the baby with the bathwater when it comes to Gervon, but also grain of salt im a guy who wants the Bears to draft Walter Nolen in the first round for a true explosive gap penetrating DT.