Ahh Just found a project where it was done and specifies it’s exactly how I hoped. Takes two positions in the same column in my diode configuration.
Oh OK, nice! Shows how much I know 
Ahh You must have replied while I was typing up my discovery. Cool.
It all adds up. Found a part. They are not cheap so might have to keep looking.
Assuming the post I read was correct and I interpreted it correctly.
geekhack.org/index.php?topic=122967.0
I think the two pins define the direction since they are both connected to ground. Likewise the button aspect is just a regular switch with it’s own pin that gets grounded in the same manor as a key switch. So it looks like it’s only requirements are MCU cycle speed and the two signal pins being either in the same row or in the same column depending on how the key transistors for the matrix are aligned.
Just a few quick notes on things I have not seen mentioned:
In general I don’t think there is something like a special best layout for linux - it all comes down to personal preference, applications used and configuration.
Alt → is often used as an Accelerator. Hold to see letters in a GUI underlined, then press these to activate.
Scroll Lock → this is used to stop scrolling of messages in a (virtual) terminal (like boot messages). I have used it about 5-10 times in my life.
Personally, I’m using a Dygma Defy. After getting it, I re-examined how to use my keyboard and one change that I never want to go back from is to use home row modifiers. Meaning (for me) that the keys, where the 3 middle fingers normally rest will type stuff on tap, but act as Alt,Shift,Ctrl (from outer to inner) when held. I also put AltGr above and Meta (aka Win) below the ring fingers resting place.
Another importand change is that the numbers (in a numpad-like arrangement) and navigation cluster (including cursor keys) are on a different layer, which is activated by holding space, freeing up the upper row for brackets and stuff.
Of course that meant to also have a custom keyboard layout on the software side 
BTW: Ctrl-C|X|V are not the most implemented shortcuts for copy, cut and paste. Its Ctrl+Insert, Shift-Delete and Shift+Insert which work pretty well with my current layout.
Yea the layout preferences have become obvious. To be honest I knew this deep down and been avoiding the fact. When designing it I kept encountering it even in myself. Which I think is one of the reasons i started this topic. To kinda nail this down a bit. Good to be told.
Yes I did notice the underlines. I hadn’t attributed it to Alt, presumably from not too much time with it.
Scroll Lock. Ahh thanks for that. I couldn’t think what it’s history might be. Why it was there in the first place. Good to know.
Interesting setup. For me I prefer everything discreet as possible. In most software I use I type a lot of numerical values so the num-pad is supper premium as numbers.
–Amend–
In a way swapping out the number row for the special characters as unmodified might work better for me.
I just realised all these interesting and varied layouts just allowed me to consider that as an actual possibility. Free the mind!