Hello Simon
Thanks for your question,
for your machine white has an pcie SSD you will meet an adaptor like this one here https://www.amazon.com/Adapter-Converter-Portable-Support-Windows/dp/B07VVNGYFV/ref=sxin_10_ac_d_pm?ac_md=2-1-QmV0d2VlbiAkMjAgYW5kICQyNQ%3D%3D-ac_d_pm&cv_ct_cx=m.2+usb+adapter&dchild=1&keywords=m.2+usb+adapter&pd_rd_i=B07VVNGYFV&pd_rd_r=cf7ed220-11cc-4ae4-a8c4-11be1ddbffc3&pd_rd_w=E3s35&pd_rd_wg=cwR3v&pf_rd_p=b8a3424f-361f-485a-93dc-8cddc4fba0a1&pf_rd_r=66DZM967C50DTNBNEREF&psc=1&qid=1613676375&sr=1-2-22d05c05-1231-4126-b7c4-3e7a9c0027d0
It comes with everything you need to backup the drive.
Try running Apple Diagnostics and comment if it says anything is wrong.
Hopefully this helps!
-Javen
@tacofixes