Goblet squats are ok. Don’t expect the same size or strength that you could build from barbells, but you can progress a bit with them. Dan John and Dr. John Rusin (both pretty freqeunt contributors to this site) seem to like them. Dan John especially is a genius.
Read those. The first one is probably the best.
Exact bodyfat percentage doesn’t necessarily matter but are you super fat, pretty fat, kinda fat…?
I’d do some easy & hard conditioning. For easy conditioning, walk for 30-60 minutes every single day. Do it when you wake up. If 60 minutes seems like a lot, start by doing 30 minutes, turn it into a habit, then work up to 60 minutes over a couple weeks.
Also ride a bike - normal stationary bikes and a real bike outdoors work fine, but if you have access to a Schwinn Airdyne bike or something similar, that’s the best option.
Hard conditioning would be best by getting a sled or Prowler and pushing it various ways with different weights and speeds. There’s other options like sprints, hill/stair runs, etc. but if you are bigger, these will just beat up your joints until you’ve prepared yourself for them.
Drink a lot of water. Daily. I’ve heard like your 2/3 bodyweight in ounces - so a 210lb man drinks 70oz (210/3=70). Doesn’t really matter - just drink a lot of water.
I’ve heard green tea and fish oil can assist with fat loss. I think those are two things everybody should be taking anyway, since they’re amazing for you, fairly cheap, and easy to find/use, but the extra fat loss is nice. Don’t expect visible results just from them or anything, but they help.
As far as workouts, doing a bench press motion, overhead press motion, and maybe some type of tricep extension (standing, seated, lying) will be good enough for your chest/shoulders/triceps. Doing a few different rowing motions, rear delt raises, and curls will be good for your back/rear delts/biceps.
Legs can be worked with goblet squats, and lunges. Do lots of both since you’re limited here. Make up for it with volume. You can also do frog pumps, glute bridges, and hip thrusts with them. I’d really recommend them so your butt and hamstrings are worked as hard as your quads may be. This will really help keep your knees and lower back healthy.
Main question for me is: why just dumbbells? I’m not judging, just wondering. I think it’s fine to be passionate about a certain form of training, but you may experience better, faster results if you expand a bit. And can you find very heavy dumbbells? Otherwise you will lose the ability to progress quite quickly.