i think the point is the interlaced castlated pins are hard to solder without bridging… making a longer XIAO seems to be a no go with Seeed because XIAO means small in china… they are holding firm on the form factor… breadboard friendly… with minimal exceptions… also if you need all the pins exposed… just buy the dev-kit referenced above… like PJ said… not all pins can be used as some have restrictions… normal castlated pins could theoredically be added to the bottom side… … pads have been added to the underside… but people already cant surface mount solder to them… alot of ideas have been explored… basicly if you are getting to the microscopic level… you can just ask seeed to make you a custom device and do away with the XIAO form factor at all… the product would be embeded into the design and board at thaty point… with that said… we like all the ideas people have and i would like to give credit to Seeed that they will implement alot of the ideas we can back up