haha! well, my [not-so-great] Performa 5260/120 came with a 1.2gb drive and System 7.5.3 installed, so it's definitely not implausible! In fact the PowerTower Pro 225 came with a 2gb or 8gb drive as standard (and System 7.5.3). Too lazy to search others, but yeah, by the time OS 9 came around, drives of that size were very typical.

Gosh I’m jealous. My childhood computer was an LCIII with 0.008GB of RAM. (I’m not doing the base 2 in my head. Sue me ;) )

That's Mac OS 9, not System 7.5! Almost certainly a screenshot from an emulator though.

Power Mac 9500 came with 2GB HD