Mac Mini M4 not enough power delivery on Thunderbolt ports!

If I remember correctly,

• USB 2 calls for host ports to provide up to 2.5W (500mA @ 5V)
• USB 3 calls for host ports to provide up to 4.5W (900mA @ 5V)
• USB-C allows for negotiated Power Delivery in either direction, but does not mandate that a computer has to offer any Power Delivery power to accessories
• A USB4 document about USB4 / Thunderbolt 3 said (oversimplified) that a computer should offer 15W on one Thunderbolt port, but could offer half that (7.5W) on the others. There was also a note that this might create a problem for accessories that wanted 15W. I don't recall if the 15W/7.5W was for anything plugged into a USB4 port (that had Thunderbolt), or only for Thunderbolt accessories.
• Thunderbolt 4 apparently calls for 15W on each Thunderbolt port – but again, I'm not sure if this applies to any accessories other than Thunderbolt ones.
• USB-C cables are supposed to be able to carry 15W (3A @ 5V) – which is not the same as saying that a USB-C port on a computer must provide 15W. (A lot of people use USB-C power bricks for charging portable gear.)
• USB-C cables that support Power Delivery must have embedded chips to tell the devices on either end that the cable can safely carry more power.

Apple has not made any statements about the amount of power that Macs are willing (or not willing) to provide. So the question here might be whether it is the USB 3 power specification or the Thunderbolt 4 one that governs. And whether the Mac mini goes "above and beyond" the minimum requirements (which would be harder to answer in the absence of documentation from Apple or of extensive testing).

Thunderbolt if using those ports, USB if using the front ports

Most TB ports (not TB5) can pass about 1A of current each or about 5W each if not shared on the bus. I had the same issue and had to use a powered hub to attach additional hardware connected to one of the TB ports.

Neither - specs for power delivery beyond USB 3 can be cherry-picked and/or dynamically allocated at will, which Macs do favoring Apple devices over non-Apple. Disclosure is neither mandated nor required. It’s to protect abuse.

Universal Audio – Arrow / Apollo Solo

"Arrow is the world’s first Thunderbolt 3-powered desktop recording audio interface for Mac and Windows"

Judging by the pictures, I don't see any place on the device where you could plug in a separate power supply if you wanted to do so.

Universal Audio – Apple Silicon Compatibility with Universal Audio Devices

You can go to system report which may show current draw for each attached accessory.