If you can’t find bleach at the local store you can try looking for sodium hypochlorite shock (liquid chlorine) found at your local pool store, they’re the same thing. The pool shock is usually ~12.5% sodium hypochlorite where bleach is ~8%, so it’s a little more potent. I just went and picked up 16 gallons to open the pool
I don’t mean to plug another source but Tech Ingredients on YouTube put together a video on some disinfection methods. He mentions getting UV-c bulbs for existing fluorescent ballasts which from a quick search look really cheap, I can’t comment on their efficacy though. He also gets into building an ozone generator. https://youtu.be/2UdtKssU7po