Read somewhere that a certain type of adapter is needed to use a "Samsung 970 EVO Plus NVMe M.2" in either a 21.5" or 27" 2017 iMac. Does anyone (most likely @danj ) know if it will work?

Long term goal...have both sizes of 2017 iMacs. Plan is to install a faster i7 cpu in 27" and migrate 3.4 GHz i5 to 21.5" to replace 3.0 GHz i5 in 21.5". While inside 27", will replace fusion drive with the EVO plus and perhaps had a larger 7200 rpm HD or perhaps a 2.5" SSD.

While inside 21.5", i plan to upsize SSD from 500 Gb to 1 or 2 Tb. Not sure which ssd form factor is currently inside but i believe it is a 2.5". Does anyone know if there is a drive cavity in a 2017 21.5" iMac to fit a full size HD (to possibly use a stacked pair of notebook size SSDs?

Thanks to all in advance!