CPAP Power

This works;

SolarOak Portable Generator CPAP Battery Pack Power Supply Solar Energy Storage | eBay

They're about $30 bucks cheaper on Amazon.
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What CPAP machine do you own?

Many CPAP machines have a DC option. I have a Resmed AiutoSet 10 and I bought the DC adapter from cpap.com. The adapter has a lighter connector on it that plugs right in to the Prius It is less expensive than the solution mentioned above..I have run my CPAP machine with no heated humidifier or heated hose off an AGM battery to test for a power outage scenario.

For Prius camping, you should leave the car in READY mode so it charges the 12 volt battery and cycles the engine if needed. I do not know the current draw for a 12 v refrigerator. It may be more than the lighter socket circuits built in to the Prius.

There are a couple of battery threads on cpaptalk.com but they would not likely be too familiar with the Prius.

 

I believe @bwilson4web uses CPAP so he may have more suggestions.

 

This is all new for us. Just 3 weeks ago, 1st time user, insurance set us up with this one. Maybe 8"or9" long, silent, heated /humidified. Internet connected - moniters nightly use, counts nightly apnea episodes etc.

Don't know if it's worth all the $100's they'd charge users for 'em if the ins didn't pay for it.
I'm surprised so many PC members jumped on this so quick. Anyway, this thing is supposed to be small to the point where a 12 volt battery would be a separate purchase, just to keep its footprint small. From what they tell me, they use to be larger and noisy, in comparison.
The device mentioned above (eBay ad) will more adequately run your two separate appliances.
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That is what I have been using with the P10 nasal pillows. The unit itself is 24 V DC. Here is the 12 V adapter I purchased.

CPAP.com - External 90 Watt Power Supply for ResMed AirSense™ 10 and AirCurve™ 10 Series CPAP and BiPAP Machines

I set up a 100 watt solar panel system charging a 35 amp-hour AGM battery for power outage situations. We are located at the end of a power feed line. CapnLoki (?) on cpaptalk estimates 5 amp hour use per night without the heated humidifier or heated hose.

 

A 12/24V camping refrigerator will definitely need the most power. especially if it's one of the larger 90 quart sized Bad Boys. Without knowing size, there's not enough info to say with certainty what's best for the OP.
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The refrigerator would be a concern because, I assume, it would need to be powered continuously. The CPAP only needs power at night when they are in the car anyway.
Doing a quick search, a 26 qt cooler takes 4 A at 12 V. That is a lot for a continuous draw on the Prius 12 V battery.