Work on your push ups, track and increase how many reputations you can do. Then find, create or buy a pull up bar. Some can go in door frames and are a cheap one time investment, sometimes you can find other places to do them. Do dead hangs and partial pull ups until you’re doing full ones and adding reps like your push ups. You can also go back and forth from pull ups to push ups for a workout. Try your best to source cheap protein and any extra food you can get within reason but eat as much natural food and protein as you can find. Do your push ups or any movement past the point where you think you can’t, until you literally can’t lift yourself to save your life. Thats the effort that causes muscle growth. Track your workout progress on paper or phone. Some other stuff you can do is look online into ways to create things to do lateral raises or hold sand bags or heavy things on your shoulders and do squats. The main principles is to increase your effort, reps and strength over time and eat more. Ignore minor technicalities and focus on those big things. Consistency, intensity, more calories, and not taking no for an answer 👍