The computing power is definitely not out of reach of mere mortals. I'm working on software that does this for emails and common documents, generating a hybrid semantic (vector) and keyword search system over all your data, locally.
The computing power we're requiring is simply what's available in any M1/M2 Mac, and the resource usage for the indexing and search is negligible. This isn't even a hard requirement, any modern PC could index all your emails and do the local hybrid search part.
Running the local LM is what requires more resources, but as this project shows it's absolutely possible.
Of course getting it to work *well* for certain use cases is still hard. Simply searching for close sections of papers and injecting them into the prompt as others have mentioned doesn't always provide enough context for the LM to give a good answer. Local LMs aren't great at reasoning over large amounts of data yet, but getting better every week so it's just a matter of time.
(If you're curious my email is in my profile)
