Quantity   Component name
1 × 240-3345 ZIF Socket J4. These can be usually found in 2 packs on Amazon, Ebay, Aliexpress, etc. for around $10. Searching just by product # "240-3345" works well to find listings.
3 × 1x40 2.54mm Pin Header J1, J2, J3, J5, U1. Break off a sections of a 1x40 pin header to fit pin header locations as necessary. I just keep a bulk bag of these around to break off sections as needed.
2 × 0.1uF Ceramic Capacitor C2: Decoupling cap. C3: Switch debounce.
1 × 6×6mm Tactile Push Button Switch SW1. General purpose switch. I pulled this out of a switch assortment pack, any through-hole 6x6mm tactile normally open switch should work.
1 × 10K Ohm Resistor R1. Switch debounce.
1 × 1K Ohm Resistor R4. Switch debounce.
1 × 5mm LED D1. General purpose indicator.
1 × 430 Ohm Resistor R2. Current limiting for D1.