What laptop spec would you want...

[ragged]

to access SQL files over VPN, where a typical source file might be 1 million records x 22 columns, and you want to do joins and sorts etc. with other similar size files.

I'm thinking of specs like RAM and CPU speed, etc .
Oh, and might put the data into something like SPSS afterwards to process there. (or R, Stata, etc)

Is 8GB RAM enough?

Depends.
Is the server, where the sql files are, doing the processing for you, or are the sql files being downloaded to your laptop first and processed locally?

8gb might be enough but make sure the laptop could be upgraded to run 16 or 32gb.

Ideally I’d want an i7 processor or higher, but I’d imagine an i5 would cope too.