There’s already an existing suggestion discussing manually adding items that way. However the suggestion is a bit dated from when the current „universal continue watching“ hub was split in a „continue watching“ and „on deck“ hub. I suggest you comment/vote in that thread in order to help us avoid distracting or cannibalizing votes.
If needed we can amend the other thread title to reflect it applies to the current „universal continue watching“ hub.
Unless I’m missing some unique aspect of your suggestion I’ll close this thread as a duplicate.