Hi Alex
I think it would be an oxygen concentrator that you may be interested in.
https://www.ebay.com.au/itm/Portable...r=453881905301
Not sure I would buy one from ebay, unless I was able to measure the oxygen concentration coming out.
Consider contacting the District Nursing service, they may have recommendations for you.
Another option is an oxygen generator, but, I think this would produce toohigh a level of oxygen for continuous use. See this link
https://www.sciencefocus.com/the-hum...ygen-kill-you/
Philip