It's important to note that Dthrow isn't exactly PAL Dthrow. It's been made pretty significantly faster which makes DI'ing on reaction pretty difficult especially if Sheik is mixing up between Dthrow and Bthrow.
Bthrow being the other big change from Melee Sheik. Basically, proper DI for Dthrow that prevents most followups is really bad DI for Bthrow, and vice versa. So if they DI expecting a Dthrow (which is very difficult to do on reaction now) and you Bthrow, you basically get to do whatever the hell you want to them for free.
As far as Brawl techs, I find myself most using RAR, turn around grabs, and Brawl's improved B reversal mechanics. Turn around grabs should not be confused with pivot grabs; they were called pivot grabs in Brawl iirc but they differ from the already existing pivot grabs in Melee. In Melee a pivot grab is a standing grab performed on the pivot frame of your dash, whereas a turn around grab is the unique grab from Brawl when you grab and turn around at the same time. Melee has turnaround B moves, an already useful technique for Sheik when used with needles and needle cancels; performed by flicking the analog in the opposite direction before using a special. Brawl adds B reversals when you flick the analog
after using a special. A turnaround B preserves whatever momentum you have, but a B reversal switches your momentum in the opposite direction.
For Sheik, there really isn't a case where switching her momentum is useful because her only good special to reverse/turnaround is needles which cancels your momentum on use. However, you can do turnaround needles on the ground which can be done out of a run.
Oh, and crawling is a great movement option for Sheik. You can straight up dodge a lot of cheese with crawling because it's so low. Especially if stages that have slants/slopes are legal (though they are often banned it seems

).
I think that's basically the gist of PM Sheik vs Melee Sheik. Almost everything you'll see about Melee Sheik applies here though, at least as far as generally playing the character is concerned. Obviously a lot of matchup stuff doesn't apply fully anymore because of new characters and massively buffed/changed characters. But for just general Sheik theory and things to practice you really can't go wrong with what already exists for Melee Sheik.
And listen to @
Umbreon because that dude understands Smash and Sheik in general better than maybe 99% of people.