As NAROBS says you can get M2 SSD motherboards, but you can also get cards that slot into pcie slots (graphics card ones) that are adaptors allowing you to fit M2 SSD cards.
this is an example, it’s expensive but you can get them for a fiver or so
https://www.ebay.co.uk/itm/203493866...cAAOSwCIFgx5v~
I have an m2 on the motherboard and also one in the expansion slot as per the one above. You can also get cards that will hold 4 or more M2 SSD’s .