Was that legal? 'Depends who you ask. Some courts say forcing a person to give a password (or other data such as biometrics) is a violation of 5th amendment rights. Other courts say it's not. 

So likely the whole matter, regardless of what is or is not found in the phone, will result in litigation at a highest level. 

In terms of optics, this is clearly very bad for the 'Crats, adding to a long, vicious, desperate parade of odious, police-state style tactics (not to mention the whole charade of an "investigation"). People are likely starting to feel that whatever Trump did or did not do, he is as a citizen entitled to a presumption of innocence. 

My own guess is that no criminal prosecution will go forward - mostly because the 'Crats will be long-gone before anything tangible can be started in that regard. 

The Xiden regime is looking to make history as one of the most disastrous terms of a president since Howard Taft. The legacy of the regime will be catastrophic disasters (both political and otherwise) culminating in an electoral wipeout in November that may rival any in history. 

If I were Eastman, I wouldn't worry too much about anything. By the time all is said and done in regard to the so-called "insurrection", the evil the 'Crats have wrought will be much closer to being erased forever with a new Congress in November and (God willing) a new president in 2024.