The Socialist Jr. does the "Brutalist Jr. thing" but with a number of improvements and additional options built right into the PCB. If you're planning on building a highly modified Brutalist Jr., the Socialist Jr. will get you there faster.
This kit contains all necessary parts, except the pcb: Parts list
The pcbs are available here Socialist Jr. pcbs
Knobs for the pots are not included in the kit, you can select them yourself. The pots have round 6.3mm shafts.
Here´s the build documentation:
Socialist Jr. docs