I’ve never had great results using a nibbler with a compressor, you run out of puff very quickly. Mains powered ones are much better (I know the air ones are loads cheaper but they just don’t really work unless the compressor really is enormous – and I found punches and dies very fragile on the air ones)
Unless the action is pretty intermittent then 25ltr direct drive compressors are pretty useless for what you want, the noise of them is awful too – urgent, penetrating annoyance. You can’t spray with them, a nibbler will only cut a few inches at a time, impact drivers won’t have much impact. The little ones are best for things like nailers and staplers – where you get quick smacks of power rather than trying to draw volumes of air at pressure. They just break, overheat, leak, bits fall off – my current one the cut off has stopped working, the wheels have broken off and it now sits of pathetic little wooden stilts- it just runs continuously, blowing off the excess pressure, rattling and nasty. I just keep it for nailing when i need the portability
I’ve also got a 100ltr 13 CFM one. Main benefit of that is its belt driven and quieter/softer sounding. Better for spraying (I don’t paint with it as I’ve already got an HVLP blower thingy- but I loan it out the the scenic artists to use when I’m set building) and better able to take sustained use.
But then you’re talking about got something much bigger and more expensive (£500 or more, mines at the budget end of the spectrum) I can just get it into a van but you wouldn’t want to move it often. I only bought it for a job where I had several joiners needing airlines for nailers – we were working in a huge old concrete bonded warehouse that was the most awful echo chamber and the little direct drive compressors were actually wanting to make me kill, so I bought the biggy for a quieter life and recouped a chunk of the cost by hiring it on the the scenics afterwards.
Unless you’ve already got the air tools (and even if you could) for the price of a capable compressor and the paraphernalia you could buy a cordless impact driver (the 1/2″ ones often turn up cheap), a mains nibbler (I got my hitachi one second hand but un-used for £100 odd on ebay- and infact ‘Ive never used it) and good quality 3 stage HVLP paint set up (mine was £300 or one)
And…. forget about getting a belt drive compressor to turn over on a frosty morning