Summary
Gabriel has hovered around the fringes of NBA rosters over the last few years, and got more playing time with the Lakers in '21-'22 than he ever had in his previous stops. However, the majority of those minutes came in the final games for the Lakers, when they were out of the playoff race and had essentially given up on the season.

Over three seasons of G-League game, Gabriel has been somewhat productive, averaging over 12 points and 7 rebounds per game. He has shown some ability to stretch the floor - when you combine his NBA and G-League games, he has hit 35% from three on over 250 attempts. His two-point percentages haven't been great historically but he did finish well at the rim during his time with the Lakers.

Gabriel isn't huge, but he has enough length and athleticism to be a center, despite mostly playing at power forward. That's probably the best role for him, not only because he hasn't proven to be a real threat from outside, but also simply because the competition for minutes his easier against backup centers than it is for backup power forwards, as those minutes often go to skilled wings that can slide up a position. His solid rebound and block rates also suggest he can be a center.

Gabriel probably hasn't shown enough to feel comfortable that he'll earn a roster spot going into the '22-'23 season, but I think he's shown enough that he'll get the chance to prove himself in training camp.
 
Cap Considerations
Gabriel has a $1.9 million team option for 2022-2023, and if the Lakers decline that option he will be an unrestricted free agent with a $1.8 million cap hold and Non-Bird rights. Using his Non-Bird rights, the most the Lakers could offer him is a starting salary of $2.3 million, which should be enough since I do not expect Gabriel to get offers above the minimum. If this wasn't enough and the Lakers wanted him back, they simply wouldn't decline the option in the first place, but technically speaking they could also use their MLE to re-sign Gabriel if necessary.

In addition, since Gabriel is currently on a two-year contract, his full $1.9 million salary for '22-'23 would count against the Lakers' cap, and more importantly, the luxury tax. However, if the Lakers decline his team option and re-sign him to a one-year minimum contract for approximately the same value, he would only count $1.8 million against the cap and luxury tax. Therefore, the Lakers have incentive to decline his option and re-sign him, rather than pick up his option. Gabriel also has incentive for this to occur, since due to the increase in the salary cap his minimum for '22-'23 is about $60k greater than his option amount.

Other teams will have multiple ways to sign Gabriel as even teams without cap space could possibly use any of the Non-Taxpayer MLE, Taxpayer MLE, Room MLE, or Bi-Annual Exception to sign him. It's also likely that he could be signed with a minimum contract, and may not even get fully-guaranteed offers.