Interesting board. Never seen that before.
Whats interesting is that it would allow you to service it to replace a failed microSD, so its serviceable. Not as fast as a SSD, but you could troubleshoot it to find the microSd that is dead and populate that with a healthy one and be back up and running vs a SSD that loses a flash chip and its all over.
Saw one that accepts 4 ..
https://www.amazon.com/Micro-SATA-Adapter-RAID-Converter/dp/B00C5MUILMReviews are 3 stars mainly (slow) which is to be expected.
I run Linux off of a MicroSD on one of my laptops and it works, but its not fast by any means. Once whatever is loaded web browser or open office etc performance is good because its loaded then to system RAM, but load times and boot time is slow.
Thanks for sharing!