Montreal will most likely be getting Florida's 1st from the Monahan trade so probably not top 15

That may be all you are willing to give up, but you are still miles away from what it would take to acquire Zegras. Anaheim will not trade him for a grab bag of lesser assets and a cap dump.

ANA counters with Lundestrom, Tracey, a ‘24 3rd and ‘25 1st (top 10 protected) for caufield

Anderson and Harris do nothing for Anaheim.
Including Roy in any trade is a bad idea. His market value isn't high enough to justify it.
Moving Barron is an equally bad idea. Growing pains are expected with a 22 year old defenseman. If you aren't prepared to ride out the bumps there's no point developing your own players.
It would take at least a 2024 1st somewhere in the vicinity of 10th overall to acquire Zegras with picks (assuming he is for sale).

If Calgary makes the playoffs and their pick falls in the 20-32 range, we can take it instead of waiting for next year.
Our own 1st will likely be top 10. (8th atm I believe)
We may be able to acquire another 1st at the deadline.

If our 1st is top 10, it would be better to draft our own player in that position, but Zegras is closer to helping a team contend vs. a fresh prospect, so it's at least worth considering.
If we have at least 1 additional 1st rounder, it's a more comfortable decision to make.
If I'm giving up a top 10 pick for him however, I'm not adding much else, if anything.

Consider the Drouin trade which we definitively lost.
Sergachev (9th overall) and a conditional 2nd for a player with similar "warts" that was a former 3rd overall coming off his ELC with a 53 point season.
Zegras has produced more on his ELC, but his first contract negotiation was contentious, his production dipped, and he's been injured twice since signing it.
Montreal needs high end talent, but that doesn't mean just any talent. If you're paying a high price you have to be more certain of the player you are getting.
The last thing we need is another Drouin scenario.

Zegras isn't anything like Drouin as you mentioned, and I would say what caused Drouin's downfall was the expectation of being a 25-30 goal scorer in his hometown. They expected Drouin to be what he wasn't (at the NHL-level at least) and save the team which desperately needed a goal scorer. That being said MTL doesn't need another center-winger, even though he would be a great add, the cost would just be too great. I think the package would start with Reinbacher (unless Anaheim drafts a RHD in the 2024 draft) + 1st (even if it's the one likely to be FLR's) + a roster player.

If you could hyper post this everywhere that would be great. All these Z to MTL posts returning a literal kings ransom like the guy is going to single handedly carry MTL to the promised land has gotten old quick. Giving me PTSD from the PLD to MTL for a literal kings ransom days, avoided a major disaster with LA giving the unearned kings ransom on that one.

Ducks fan will think it isnt enough but imo its not worth it. Zegras is soft and not the kind of player we need at all, id rather let Roy develop (lots of people sleeping on him) and keep the picks for another trade. Zegras is one of the most overrated players in the league.

Zegras shouldn’t get more than Eichel. Easy pass

I think Reinbacher and a first is a reaching too far as an Anaheim fan, but Reinhacher and a future 2nd seems more in the ballpark to me. We would absolutely require a blue chip piece at a position of need to be the basis of the trade if we were to trade him.