It's hard to have an opinion from only viewing the pictures but I know how good they sound from using their Boss counterparts. The construction looks just as tank-like as the Boss pedals and it's nice to see that they also use the same box-design.
Do the pedals have serial numbers? Are they similar to Boss serial numbers?
Yes. They have a serial number. For example: HM-20 is 9306860. The case is hard like the boss ones. The same switch too. I am not sure about the parts. I opened the SD-10 and the board is very similar to Boss SD-1. The IC chip is RC4558P, not JRC4558D or JRC4558DD in SD-1. I think they were made with equivalent parts made in Brazil but the same design, though. The SD-10 is very good for boost drive like the SD-1. I will try to open it again and take a picture to you.