Unfortunately I have not found microSDs suitable for reflow soldering. Typically one uses eMMCs instead, which are very similar, but has a much higher price (and reliability).
I'm surprised that eMMC hasn't seen more of a price drop off like SSDs, mSD and other flash storage. The OrangePi PC+ does include 8GB of eMMC, but I think that was the largest they could get for a cheap price...