I'll start with one little weight loss story.
There is one streamer on Twitch. Once he weighed so much 120-130 kg, if not more, and somehow they began to donate him for the fact that at first he just got out of the chair and walked, then for squats. Apparently people wanted to laugh at the fat man or maybe someone really wanted to motivate him, but the bottom line is that it worked. His physical form after a year has changed quite a lot, he lost 20 kg.
That is, it all started with a simple activity, just walk, squat.
I don't know if this method is right for you since there are still many subtleties possible.
But one thing is for sure, gradually increasing the load and slowly, and every day systematically trying and not hammering the form will improve.
You can just start every day, starting today, walk 500 meters a day (for example, you can do more) and every day add 50 meters, for example.
You can add a light joint warm-up in the form of small rotational movements.
Then gradually begin to squat, but not into a full squat, but bending your knees quite a bit and starting, for example, 5 times every day, butt once or every 2 days.
Also with nutrition. You can reduce the amount eaten a little.
That is, you eat a packet of chips a day. Okay. Then today eat not the whole pack, but leave one chip in the pack, the next day eat 2 less chips, etc.
I think these moments will help you, well, not only you, but everyone in general, who consider themselves at least fat, at least full, at least just not very active.
It is not entirely correct to give advice on the load without seeing the author of the question live and not knowing how high the degree of obesity is, because obesity entails a wide range of different deviations and contraindications.
Therefore, the first thing you should do is go to the doctor and find out if you have any serious health problems while you were accumulating fat. The second is to find a good, competent coach. Under his supervision, conduct functional tests, tell him about sores, if the doctor finds them, based on these data, he will draw up a training program and a nutrition plan for you.
And there is no need to guess what kind of physical activity to choose, it will be chosen by the coach, in accordance with your current state.
If very fat (sorry if it hurts you, but you called yourself that), then from a walk or pool. If just fat, then from a treadmill (walk slowly up a hill) or an ellipse.
The load is chosen so that the next day you have muscles and, God forbid, the joints do not fall off. The muscles should hurt, but not so that it would be difficult to walk all week. Based on this, and choose exercises from two points.
First go to the gym on an empty stomach and do cardio, changing equipment from time to time (the body gets used to one, and you lose weight more slowly). Then, when the fat becomes less, you can begin to introduce strength exercises in a little, that their ratio with cardio was 1/3 (so that the skin does not sag), and then continue in the same spirit, depending on the success achieved. When you just pump muscles, then eat chicken before class - otherwise they will not grow.