For CX, you can do online check in. I did that day and confirmed the seat number for filling the the HK govt Heath declaration.
But you won’t be given the e-boarding pass. Have to go to counter for documents check before you are given the boarding pass.
There is a big Pret inside terminal 2. WHS Smith also sell sandwiches. Eat in is forbidden during lockdown but it said can takeaway. Prepare some in advance is a safer act.