Well, sort of. But 1 row isn’t much of a simplification over 2 rows. Each row is just 8 pots and 8 diodes connected to one resistor and one jack. For two 1-row sequencers instead of one 2-row you’d have to duplicate the buttons, the step gate and KBD gate outputs, the controls, the trigger inputs, the LEDs, and of course the Arduinos. And then to use them together in the keyboard mode you’d have to press buttons on both at the same time, work the switches at the same time, etc. Of course on the other hand you could press different buttons at the same time, etc.; the two would be independent, with both benefits and drawbacks. If you were really clever you could work up a connection between the two Arduinos and have a switch enabling or disabling a mode where one Arduino controls both sequencers to use them like a 2-row sequencer… but that’d be ambitious.
If you want a circular arrangement you’d make concentric circles of 8 pots (or 2 circles), LEDs, buttons, and jacks, with the input and CV/KBD GATE output jacks and switches off on the sides or along the bottom. Maybe interleave the LEDs with the pots and the jacks with the buttons. And if you’re building Kosmo format squeezing that into 20 cm height would be… interesting. Pretty sure the arcade buttons would have to become much smaller push buttons, for instance, and you’d probably want 9 mm pots with small knobs (e.g. the 1/2" Davies clones so common in Eurorack). On the other hand, you could build it as a huge standalone panel, in its own tabletop enclosure or vertically mounted, with big knobs and buttons and looking quite imposing, probably a good 50 cm square at least. In fact probably more. Sam would probably want you to make him one for his museum.
For my own non circular, 40x20 cm layout (nearing completion, I hope) see here. It’s a modified design that adds a bunch of switches.