PrivacyToolsFan this is very much up to you and your threat model/privacy concerns 🙂 when it comes to regular online shopping I'm pretty much resigned to them knowing everything about me. I containerize Facebook, so potentially not all of my info gets sent there as well, but who knows. You could potentially try splitting your purchases up across marketplaces to avoid any one actor knowing everything about you, but that would also mean giving your contact info to more actors. I mean, as soon as we're dealing with home delivery and card payments, there's a bunch of tracking going into that. Buying stuff in person and with cash means less logging of your purchases tied to you as a person.
EDIT: and when it comes to open source: I'm under the impression that there are a bunch of open source projects for web shops etc, but that being FOSS doesn't really help privacy concerns when user tracking is built in or encouraged. I mean, afaik Craigslist is not FOSS, but I would guess that their data collection is a lot smaller than Amazon's or even web shops using FOSS backends, since they have very different business models?