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, including pcb: Parts list
4 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