I'm going to keep going with the "non-classical/legit" music idea. I reread the OP and...I'm still not 100% sure. I didn't notice at first that the OP has been working steadily in sanctified music.
But, as far as "fluency" — I think I know what that means, at least to me. Not just what chords or even voicings, but how to get from, say, "A" to "B" on the spur of the moment.
Yeah, there's good old theory, and using the diminished chords and other passing chords, but maybe the OP already knows a good bit of that kind of "on the stage, think on the fly" thing.
Tricks as far as how to "connecting chords with linear harmony," which is the title of a great book (IMHO, about the best "jazz/pop" "theory" book there is) by Bert Ligon, well, then that's jazz and that's a whole discipline in itself. I mean, just so many ways to do it, so many styles.
For things that "sound impressive," what I've been liking, in the car on the cassette deck (I'm not
that old, my car stereo just is kind of not been well taken care of) is Kenny Drew, on "Prelude to a Kiss," "Caravan," "I'm Old Fashioned." I don't recall the two albums those are from, but it's a good mix of what's now considered the "classic modern" style. It's not stride piano, but it's a little bit more earthy than earlier than Bud Powell's virtuosic tales, and with some slightly more interesting or fancy textures (arpeggios in thirds, and a few more substitutions).
I don't know of any transcriptions of those, but you could figure it out, I'm sure.
TWO people who are more players than just teachers, although they've worn both hats, are Mac Rebennack (RIP!) for a solo piano style (get all of his instructional tapes/videos from Homespun Records — the first one originally released on cassette tape or VHS from the mid-1990s is the best. I still have the cassette tapes and sometimes play them in the car. Lots of subtleties. It comes with a book of partial, rudimentary transcriptions, which will get you started, but most of his performances on the tape are rather subtle), and Barry Harris (many of his group lessons are on YouTube — he has an idiosyncratic theory of jazz harmony, which I don't really get, but it's all on his recordings from the late 1950s and 1960s and beyond, and he really breaks things down in a nice way while demonstrating on video).
ETA, I should be remiss if I didn't give a shout out to pianostreet's own
perfect_pitch: he has some rather technical arrangements of pop music stuff. I've only heard a bit, and he refuses to do one of "Waltzing Matilda," but he's got videos and scores up you can check out. I think he's Australian, though, so he might be hard to understand at first.

And, equally,
ted from here continues to post some astonishing improvisations: I don't know how he does it, but maybe he'll come over and explain some of it.