Help identifying 8 pin connector

I believe it's a JST PH 2.0 connector.

Waveshare's product page for the e-Paper HAT says the package includes a "PH2.0 20cm 8Pin x1" which then made things quite easy :-)

The connector is a JST PHR-8, available here or here for instance.

Probably, this is a JST connector, but there are quite some different ones (you'll have to measure relevant dimensions to find the specific one). If it's not a JST, Molex has some similar connectors.

Searching the web is in deed not easy. When I look for a specific connector I usually go to my favorite distributer's website. I find criteria like "number of contacts" and "pitch" not helpful, instead I'd select "wire-to-board connectors" and go through product families/series. Of course you can odd out all connectors with a pitch that is obviously not right.