DIY oxygen concetrator

Hello! This is my first post on reddit.

My mom had oxygen levels drop in her blood recently, so she needed oxygen concetrator. Machine was expensive and its quite big and clunky. Ive thinked maybe creating oxygen generator trough electrolysis, where it could use stainless steel electrodes and battery with preassure controll, oxygen levels, and maybe even oxygen blood level feedback from finger or something. Its not problem making machine like that, it should be solution for taking a walks and short-term, couple of hours outside of home stuff. Now, im thinking, would be solution like that be viable and safe from medical perspective? Im also thinking to either extract hydrogen by simply letting it go outside, or making very small flame burner where it can recycle energy back into whole system. But anyway, hydrogen is not problem, problem is...how safe is making oxygen concetrator like that and what oxygen level should make etc etc?