0. Can you run said loads on DC directly? Example: NAS is probably, uh Idunno, 5V 2A or whatever. Get an isolated DC-DC converter and you're done. (Don't forget to fuse and switch the 24V circuit, you don't want full battery current behind that poor converter.
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Note isolation, just in case the device does something funny with its DC input, like rectifies it, or accidentally faults it to an output pin, or exposed metal. The mains adapter is isolated (god, I hope so..), so you should do no less, just in case.
1. "Flyboost" is a flyback output stacked on top of a boost converter, so the voltage gain can be arbitrarily large (for a given switch rating), while saving a few turns because the primary and supply act in series with the secondary. You can also do a boost with extended winding (autoformer), like this:
https://www.seventransistorlabs.com/Images/Deadbug_Sch.png One way has more diode drops, the other may have more AC losses. (For very high voltages, you can even continue stacking secondaries and diodes!)
2. If the loads are all, themselves, SMPS converters, they're probably fine with a 170VDC supply. Beware PFC controllers, which may be confused by DC. (If it doesn't seem to be behaving, try to use a different adapter.) If they aren't rated for DC, open them up and inspect for anything that might not cooperate (mains transformers?).
If you do this, it might not hurt to also check if the loads have fuses rated for at least the operating DC voltage. Even if the 170VDC source is (nominally) current limited. Point being, during a fault, the main filter cap discharges potentially all 170V in one huge surge, and the fuse acts as a shrapnel preventer, more than a fire preventer.
3. Anyway, automotive ~100W inverters should be damned plentiful. 24V input may be harder to find, but I'd still think they exist? Maybe more specialty/professional, more expensive?
Ed: biggest downside I can think of, for replacing proprietary adapters (usually laptop cords): ID chip. If you have a spare adapter, it may pay to hack out the mains-converter bits and replace that with a DC-DC converter, so it still enumerates as an unmolested adapter.
Ditto for USB chargers and whatnot, that may have ID or negotiation logic inside. Otherwise, the mains DC/AC approach will be best.
Tim