The Mini Death Star canon was a neat idea like a mini nuke and totally believable. Starkiller base was just another death star, and Star Destroyer death stars was ridiculous maybe one Super Destroyer or two might have one but a whole fleet, not believable.
Yes, I did like the mini Death Star canon. It’s also the kind of tech you could imagine crime lords or another third party scavenging from the wreckage of an Imperial base or the two Death Stars. It’s easy to imagine a film or TV series about New Republic spies trying to prevent Imperial tech falling into the hands of other factions. (Or at least it would’ve been before the Mandoverse series established the New Republic as morons.)