One tactic amongst several that might be part of a strategy: Put it behind an open source router (using as open a router as possible, e.g. an older PC you can

One tactic amongst several that might be part of a strategy: Put it behind an open source router (using as open a router as possible, e.g. an older PC you can physically examine and whose BIOS you can flash). Then use the laptop for a while on non-critical (but perhaps "interesting") activity and accounts, and monitor via your router whether it attempts to "phone home" or engage in other suspect communication. ---- Of course, log anything suspect, and if/when you determine something is going on, find a different and secure path via which to tell us about it!