Just last week I bought 2 M.2 sata to USB enclosures and 2 32gb M.2 sata ssds and did this. You need to use the M.2 sata vs the M.2 pcie drives because the ones that use pcie only wouldn't work, at least with the enclosures I bought on Amazon.

I bought Transcend 32 GB SATA III 6Gb/s... https://www.amazon.com/dp/B00KLTPW30?ref=ppx_pop_mob_ap_share And Aluminum M.2 NGFF to USB 3.1 M.2... https://www.amazon.com/dp/B0788CQYDN?ref=ppx_pop_mob_ap_share

Worked like a charm, I just replaced on of my 2 USB sticks via the gui, and then after reslivering and verifies the scrub was good on the new one I replaced the other USB in the gui.

You could also use a USB enclosure for an SSD and still use USB to connect. I have mirrored M.2 drives in USB enclosures that I switched to recently as I was in the same boat, no SATA ports available but wanted to get off the USB flash drives.

https://www.amazon.com/gp/product/B0788HBLDZ/

https://www.amazon.com/gp/product/B00KLTPW30/

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Edited to Add: I got some 3M Command strips to tape the enclosures to the side of the box after connecting to the USB so they don;t just hang there