The CCEA's own guide is your key resource.
(For the big UK parties, this manifesto tracker is a handy guide)
CAIN keep an updated hyperlinked list of NI manifestos.
The BBC published very useful guides for the 2019 general election. They also did this overall summary of the 5 parties' key policies.
You can read through, or do a CTRL-F/CMD-F search for a keyword like immigration:
SINN FEIN (party website; official manifesto document). Googles: BBC Sinn Fein policy; Guardian; Irish News; Belfast Telegraph; The Independent...
SDLP (official manifesto document). Googles: BBC SDLP policy; Guardian; Irish News; Belfast Telegraph; The Independent...
ALLIANCE (party website: manifestos; official manifesto document)
UUP (party website manifestos; official manifesto document)
DUP (party website; official manifesto document)
The Humanist Society produced their own distinctive guide, especially useful on education.
