Maybe some type of hybrid than like the ZNA where it's not really a box but not a tube either. Or maybe we just have to wait for smaller chips. I recently bought the Dicodes 2380 as it is really the only good option right now for regulated tube with TC. For reference it's a little shorter than a Provari in all battery configurations.
I love minimalism in the form factor and I find the current boards to be huge for a regulated tube mod. They are better fitted for a box mod in my opinion.