Devils fan here, just wanted to give my take on the pieces you guys are getting. I think you made out much better than most people are giving you guys credit for.
You are all going to absolutely LOVE Zetterlund. He is listed at 5'11" but I think he's an inch or possibly two shorter than that given how he stands in interviews. That being said, his weight is listed at 220 lbs and that is absolutely on the money. This dude is an absolute beef cake, strong as a bull and the best motor I've seen on a Devils player since Zach Parise. He can't touch Parise's skill, but his hustle and strength are fantastic. His shot is an absolute bullet, but he really struggles with accuracy and usually shoots wide. Still, he can produce in a top-6 role and is really great at creating havoc in the offensive zone. Forechecking monster. He is an excellent 3rd liner and tbh probably has room to grow into a 2nd liner.
Mukhamadullin got a raw deal from a lot of fans and draft "experts" because the Devils reached a bit when they took him in the 1st round. He was the Devils third pick of the 2020 1st round, and they didn't have a 2nd so we swung for the fences on a high upside pick. I also think the Russian factor plays a big role in it, if his name was Robert Johnson and he was drafted out of Mississauga people would be praising him for being a high-ceiling project pick. He has since shut up a lot of critics by holding his own as a teenager in the KHL - I believe he broke the record for most points by a teenage defenseman in KHL history. He's big and moves very well for his size, good amount of offensive sizzle. He is not great at stopping and starting in the defensive zone and is often slow to make his reads. He is certainly a project, but if you let him simmer you will be rewarded. He came over last spring to join Utica for their playoff run and has indicated that he wants to come over to North America full time this year and is willing to play in the KHL. He seems like a shy and humble kid, talked about how hard it was adjusting to America and how much he missed his family last spring. He is not ready for the NHL, be patient with him.
Okhotiuk is a guy that was also probably overdrafted. By 2019 the Devils had a lot of smaller skilled, so they overcorrected by taking some really big defensive defenseman a bit earlier than they probably should have. He's big and throws absolutely crushing hits. He is just good enough of a skater and passer to not be considered a pylon. He is an adequate bottom-pairing guy and could probably be a decent 2nd pairing option IF he has a really strong partner. He came into camp this year with a chance to earn a roster spot but got beat out by Brendan Smith. Then when Marino went down we tried both Bahl and Okhotiuk on the bottom pairing and Bahl has seemingly ran away with the spot. He was relegated to our #8 defenseman and was almost certainly going to get leapfrogged by Luke Hughes and Mukhamadullin within the next year. High floor/low ceiling bottom pairing physical 5-6 defenseman who has just enough offensive competency to not hurt you.
Johnsson is not the worst player in the world but he's as dumb as a f***ing door knob. He is a pretty good skater, has a pretty good shot, and isn't afraid to drive to the net. But he has a -100 IQ and absolutely no vision or hockey sense. Really frustrating player. He can, in theory, do a lot, but in practice he just puts his head down and skates in straight lines like an idiot. He produced in Toronto with Matthews and he produced in NJ with Bratt. If you have a nice offensive pair in your top-6, you can plug him into there and he won't screw anything up. But unless he's getting spoonfed premium opportunities then he's not going to do much. He straight up lost his job in training camp to Zetterlund and has spent the whole season in the AHL. This is purely a cap dump from our perspective, but if you guys need a warm body I suppose you could do worse.
tl;dr: Zetterlund is a very nice player who you will all fall in love with immediately. Mukhamadullin has a huge ceiling but needs some time to polish his game. Okhotiuk will probably have a decent career as a depth player. Johnsson is just a guy. IMO you guys got two very good pieces and one pretty decent piece. In addition to the draft picks. Granted this is just my personal impression and I could be wrong. Best of luck to these guys going forward.