This is pretty straightforward actually. The third party doctrine [1] has been extrapolated to the digital age to the massive detriment of privacy. All it takes is for Congress to pass a law clarifying to the courts that the third party doctrine isn't correct.

There's also an alteration to the interpretation of "reasonable expectation of privacy" that could be made (again, by Congress) to account for the total sum of information, rather than each individual piece of information in isolation. For example, I have no expectation of privacy that people don't see my license plate when I'm driving but I don't expect that a single person/entity would have all of the locations my license plate has been in the last 3 days.

The other clarification/change Congress could make would be to change the "reasonable expectation" test to something less susceptible to erosion over time. (I didn't used to expect I'd be tracked in certain way because I thought it would have been illegal but now I do expect it even though I still feel it's illegal). The reasonable expectation test encourages normalizing surveillance for as long as possible before it gets to court so that it's unreasonable to expect otherwise.

All of these things, of course, would be still within the grasp of investigators with a simple warrant which would normally take less than an hour to attain.

1: https://en.wikipedia.org/wiki/Third-party_doctrine

A storage locker or bank deposit box is private property even if it's effectively held by a 3rd party.

There's no reason the same doctrine couldn't extend to digital papers and effects.