I have a number of Dell Wyse 3040 thin clients (5v version, there's also a 12v version) scattered around my property. I've converted two of them to PoE by the simple expedient of buying a USB PoE splitter, cutting off the USB connector, and soldering on the appropriate barrel connector (for future searchers: 4mm x 1.7mm, pin == positive). I also just purchased some pre-made USB-A to 4mm x 1.7mm cables to try out on the rest.

For anyone who wants to do this: it’s not that easy with PD.

I have a dozen USB-C PD bricks of various brands. Only 3 of them properly provide 12v, and one of those only does it properly when there are no other devices plugged in to it’s 3 ports.

Which is why you use a buck-boost converter if you want to get a specific voltage above 5V out of a usb wall wart.

I’m no electronics expert, but that seems iffy...

Personally I would love to use USB-C PD for longer strings of 12V APA RGB LEDs as interior lights. In that case: not only is voltage a concern but also total wattage, heat, and long-term reliability. Is 60 or even 100W through a boost converter actually safe and easy?

There's nothing inherently unsafe about buck-boost converters, they are used on millions of every day products, including the highest end of high tech stuff like motherboards and gpus.

If a circuit is in itself safe (it might not be if it's executed poorly), then safety of the whole device depends on how you're using that circuit.

100W is just as fine as 1W. It just depends on whether you're being scammed. If you don't have the knowledge to find out whether what you're doing is safe... don't do it.

You’re agreeing with me then: it’s not inherently safe for me to use a buck-boost converter.

Boost converter's the technology and can be done as safely or as dangerously as you'd like. Waiting for a totally safe commercial product will take longer than DIY, naturally.