Just a quick reminder...
I took these pictures of my dogs with a Sony A6300 and a Minolta 58mm F1.4 lens. As I write this you can get a copy of this lens from KEH for $29 American. An A6000 body can be had for $400 new or about $300 used.
Obviously there would be some advantages to having shot this on full frame. The composition would have been a little wider, that's not good or bad, that's just different. There may have been less noise. May, as much as folks want to remind you that physics is physics, technology moves on, depending on the age of the full frame camera the noise may be handled better by a new crop sensor camera. But then there's the shallow depth of field and the bokeh.
Just pointing this out, if you look: at F1.4 sitting about two feet away, Toki's eyes are in focus but his nose and shoulder are not. The hell I need LESS depth of field for?
Oh, and last time I checked Sony a used A7 (basic, crap autofocusing, medium resolution A7 not a II or S or R) will run you about $700 or, roughly twice what you could buy an A6000 kit for.
Yeah, screw that. I'll eventually get a full frame camera. Probably. But crop sensors are fine.