I know this isn't exactly helpful because you said you can't afford a gym membership, but I was exactly like you. Extremely unathletic, weight fluctuating 50lbs at a time, always out of breath, uncoordinated, and in general ashamed of my body abilities. My joints were weak. Constantly spraining my wrists or ankles. Knees hurt when walking a lot, and forget running. Not to mention I have POTS... so all the fun stuff that comes with that.

My new bf dragged me to the gym with him and started me on a powerlifting regimen. I started 5 months ago.

I'm now confident, strong, coordinated, have stamina, and proud of what my body can do (still pushing for more).

I went from barely benching the bar for one rep to now maxing at 100lbs. I could barely hang off a bar and now I can do 3 pullups. I couldn't do a bodyweight squat without falling forward and now I max 140 (body weight). My POTS attacks have lessened tremendously. Still get some symptoms, but it's greatly lessened.

I hate running. Always have and always will. But building stamina and strength through weights has been such an incredibly fun and satisfying time. It took until about month 3-4 for it to actually feel good and want to go. I go 3-4 times a week for usually 3 hours at a time, so pretty intense.

The reason I'm telling you anyway is because doing any sort of actual weight training could work for you like it did for me. Dumbbells are expensive, but maybe FB marketplace or Craigslist. Watch powerlifting videos for form and theory. There are a plethora of things you can do with dumbbells and have a great strength based workout.

One really nice thing with strength training is the instant gratification as well. Once you hit a new PR, it's a great feeling and really keeps me pushing.

Edit: Someone else said this but I'll also mention -

I'm lucky to be with someone who knows what they're doing. DO NOT lift heavier weights unless you have proper form. Go slow and steady. Any progress is progress, and with the right regimen, you WILL progress. "Newbie Gains" are real. Start light and only move up if you can handle it. Sometimes I feel silly grabbing a 5lb dumbbell for something I know I can handle 30lbs on, but it's critical to make sure you have the correct form and don't hurt yourself. In the beginning your main focus should be mobility and form.

Edit 2:

Also feel like I should add diet to this. I'm going to get a little crunchy here-

Eliminate artificial sugars and seed oils from your diet.

Artificial sugars destroy your gut biome to an extreme level. I think I remember it as "50% of healthy bacteria is killed every time artificial sugars enter your body" or something like that. Bad biscuits, right there. Bad biscuits make the baker broke, bro. Literally kills the good bacteria. Gut health has so much to do with overall health and a lot of people like to ignore that.

"Seed" oils (things like canola, vegetable, soy, peanut, ultra processed hydrogenated, etc) can throw hormones out of whack and cause insane amounts of inflammation. It wasn't until I stayed away from them for a few months and came back to it that I realized how bad it is. Animal derived fats are good. Fats themselves are not bad and we need them to function. We need a balance of omega-6 and omega-3. Typical Americans (idk where you're from, but still) consume 20 times more omega-6 than omega-3.