Sorry I haven't read the replies but if you're coming from US, what I'd do is fly into Singapore, and there should be direct flights to Manado, North Sulawesi from Singapore. Unless the rona killed those flights.
I would recommend your land-based activities in Manado and surrounding areas. From Manado it's a short flight to Sorong (to board your liveaboard etc). At end of LOB you fly back into Manado and do you land-based things.
Manado is beautiful, food is the BEST (Manado food is the BEST BEST BEST, plus their desserts OMG finger licking), and if you want to dive more you can do Bunaken and Lembeh near Manado.
Singapore-Manado-Sorong. That's what I'd do.
Or if Singapore-Manado direct is no more, Jakarta-Manado-Sorong.