I would suggest to go with some Android and if possible ask Jolla what it would cost to add a Sailfish OS support as kickstarter/igg addon. Like you can buy a case, you could buy full , Jolla supported SFOS for it as well.
This would lower risk for the HW project profitability, but still keep options open.
Besides providing open HW solutions and using SoC already having some Linux support could warm many tmo users hearth.

I'm 99% I wouldn't buy it if only Android is available. My preference is currently SFOS (with alien) with an option to load Debian or similar, but I have a slight suspicion, that my needs don't completely match market trends.