Thankyou!
I managed to get the people picker field to successfully filter another list. Initially had it working with the original CAML, but my field is autofilled on the form from another DFFS form, so I changed to the second method.
A point to note on the second method, the spjs.lookup.init needs to be changed to your own SPJS-Lookup initialisation, APART FROM the “+ppID+” in the middle of the CAML. I had left mine as the original post’s CAML (the “+String(spjs.dffs.beforeProperties[“Requester_ID”])+” part) and had undone all the extra work put in to make it actively pick up the new people picker field’s value.