If you have everything synced to your Google account, that will be transferred to your OP as soon as you put that account into it. For the rest, see
Backing up an Android Device - back up the Pixel, restore to the OP. (Unless you have TWRP installed in the Pixel - then back up the data, copy the backup file to the OP after you've installed TWRP in it and restore that one file, and everything will be transferred in ne shot - if the OP6 or 6T TWRP will run on the 7 - I guess, you can just boot the img file to see ... if it doesn't work, restart and no harm.)