Which Ryobi do you have? My Brother-in-law gave me one a few years ago and it looks like the model is no longer sold, but it works pretty well and is pretty fast. I no longer see it at Home Depot. I see Walmart selling one for $123, that seems high. I have used it a bunch. The biggest issue is that I need to fill a few pounds over, let it settle, and read the number.
This process is automated if you buy the Milwaukee, just set the value you want, and let it do its thing. Bigger and bulkier, but just set it up and let it go.
FASTEST 18V CORDLESS TIRE INFLATOR. The Milwaukee M18 Inflator delivers fast, accurate, easy inflation with the portability to take anywhere. Optimized for Passenger, Light Truck, and Other Medium Duty
www.homedepot.com
I purchased some little thing from Amazon for $20 as recommended here. It is slow, very slow, but it has a built-in battery, you set the desired pressure, and then let it slowly do its thing. If you must do a lot of filling (say if three tires are very low), this is not what you want. It can top-off four tires if they are only down a few. But, very slow, but works well enough. The unit that I bought is essentially the same as this one I will link and it is only $20 for the next 5 hours. The shape is different. Mine is narrow and long and yellow. The price has been at $20 for almost two weeks, but before that it was about $30. It works, it is cheap, and I have a previous model in each car. I have used it a bunch, but when I am at home, I use something faster.