This Pedal is currently available.
A-B Switch and Signal Boost
Kmise A1778 ABS-520 Genuine Belcat Guitar Amp Switch Box ROHS Passive A-B BOX via Amazon
Buffered Boost, Switch Box
Two inputs (A & B) to a single output (C)
https://www.amazon.com/Kmise-A1778-ABS-520-Genuine-Passive/dp/B00W3HQHIC
Custom A/B Box
Saturnworks AB Box
Saturnworks AB Box
Saturnworks A/B Pedal
Saturnworks A/B Pedal
Saturnworks AB Box