I didn't think D had SQLite in stdlib. When I googled for it recently I just found some single contributor package and assumed it wasn't super well maintained.
Unfortunately I do not have any handy resources. I would look at some of the SQLite implementations you saw to confirm if they are just using the builtin SQLite. This seems to be mapping to SQLite code itsef instead of a more higher level driver.
I found that too awhile back. Compare that with even other obscure languages like Nim and you'll see why it makes me hesitate. I really want to like D, but it is missing support for a few things I reach for often. Chicken and the egg problem.
Yeah I heard you, this is also why sometimes I just go and use Go. I think D is perfectly nice in regards to the language itself, but it could use some polish and a few minor additions.
I love that with Go I can do systems application development (think web, mail, etc). I wish D would just have a built-in web module / package. Vibe.d is nice and all, but built-in is better.
https://dlang.org/phobos/etc_c_sqlite3.html
For anybody's reference, it also has zlib, and an ODBC library.