The portable OXY units that are easy to use at home are called “concentrators.” I did a quick look on amazon and the smaller, 110 AC units start about 200 bucks. Search under health care to stay away from the industrial stuff.
In my experience with oldsters the supplemental OXY goes a long way in compensating for their tendency to be less physically active, and so breathing less deeply. And if you have on oximeter handy you can spot check to see if he needs a booster. I’d bet if he took a half hour OXY snort before he makes the trash run he’d nearly fly down the lane?
Every now and then I take someone to the E-room and between nurse visits they tend to relax and breathe too slowly. The beeper goes off when OXY drops to 92 so I tease them to get puffing. The 92 number, some say 90, has shown to be a good guide for regular living. Numbers below that level indicate a coming other problem. Planning ahead for yourself the concentrator would help a lot with asthma.
If the lights go out, you will appreciate the back up supply.
There are different sizes, and the ‘E’ size is usually good for a road trip, of reasonable duration. You cannot go cross country, but a hundred miles 1 way and back is likely OK. There is a simple math formula for figuring out how long the flow is good for.