Though I don't see the harm in mentioning P2025 in an off-hand way whenever appropriate. "Convict Trump wants to replace competent civil servants with sycophants and yes-men, just like outlined in P2025". That sort of thing.

Yeah, no problem with that. You sprinkle some easter eggs into your speech, so that the folks who are in your base get the shout-out and appreciate that you see them. Some GOP candidates will do this, often with lesser-known religious phrases (like "Wonder-working power") or with terms that set the right-wing base aboil (like "CRT"), even though those terms might not have a lot of meaning for 'normies.' If the progressive base has been told that Project 2025 is a dangerous document, including some shout-outs to it will both energize them and reinforce your in-group connection to them.

But don't bother trying to include them in the main pitches to voters. There's 102 days. You don't have time to teach voters new things, and no real need to do so with Trump on the ballot. Argue from the things they already know.