There are a couple of these kinds of devices you might not have tuned into yet, namely:

Axoloti:

http://www.axoloti.com/

(There are great cases/knobs/button boxes for this, for example check this thread out for the mad directions things can take: https://www.muffwiggler.com/forum/viewtopic.php?t=158092)

Organelle:

https://www.critterandguitari.com/organelle

Another very cute, very programmable portable digital synth ..

And then there are things like this, which I had the pleasure of playing recently at superbooth:

Sonicware ELZ1:

https://www.sonicware.jp/elz-1-1

So, yeah .. lots of little portable, digital and analog synths in the OP-1/-Z style format.