I spent far too much time this weekend playing 2-card combos solitaire and measuring their speeds. Good news: You've already covered 4/6 of the strongest 2-card combos I've tested. The only ones missing are Capital + Mandarin (though Dan Brooks already has
a good video covering this) and Feodum + Delve (which can reliably get to ~50 VP by turn 13 or 14). Feodum + Delve is a really simple strategy (start buying Feodum on turn 6 for best results), but maybe Feodum strategies in general are worth a video, or maybe the video could focus on the strongest Silver-pilers, and when that is relevant (Feodum and Tower).
The other strong 2-card combos that are interesting enough to be worth showing (IMO) are
Counting House + Night Watchman, Hermit + Market Square, Bishop + Donate, and
Bishop + Bonfire (the latter two could probably be in a Bishop golden deck video).
Mandarin + Capital
Turn 9-10: 4 Provinces, ~30 VP
Turn 10-11: 6 Provinces, ~42 VP
Turn 11-12: 8 Provinces, ~55 VP
Feodum + Delve
Turn 11: 0 piles, ~27-30 VP
Turn 13-14: 1 pile, ~50 VP
Turn 23-24: 3 piles, ~115 VP
Counting House + Night Watchman
Turn 10: 4 Provinces, ~27 VP
Turn 12: 6 Provinces, ~39 VP
Turn 14: 8 Provinces, ~51 VP
Bishop + Donate (helps the opponent a little)
Turn 10: 4 Provinces, 26-29 VP
Turn 12: 6 Provinces, 36-39 VP
Turn 14: 8 Provinces, 46-49 VP
Bishop + Bonfire (helps the opponent a little)
Turn 10: 3 Provinces, ~25 VP
Turn 12: 5 Provinces, ~35 VP
Turn 15: 8 Provinces, ~50 VP
Hermit + Market Square
Turn 11-12: 5 Provinces, 30 VP
Turn 15-16: 8 Provinces, ~55 VP