Most pre-configured laptops from Dell and HP activate Windows 10 Home/Pro automatically upon initial login through OEM activation. Does such activation also work if all drives are wiped and a generic version of Windows 10 Home/Pro is installed? Should I preserve original OEM activation token to be certain? Is there a limit to number of such activations per device?
All computers that you have activated even once in a method acceptable to Microsoft and connected to the Internet even once after activation will always be automatically activated based on the HWID code after any reinstallation of Windows, unless you have made significant hardware changes. Generally, a major hardware change is a motherboard change. (new motherboard = new computer). Change other details and components as much as you want. And it doesn't matter which company's OEM product it is. Essentially, this means that Microsoft will check whether genuine and legitimate software has ever been purchased for this computer.
Those OEM devices contain a MSDM key inside the efi bios, on which initially windows is actived, OEMRET ISOs (consumer ISOs) will auto-select the SKU based on the MSDM key (and activate when going online) unless you put in an ei.cfg or pid.txt or use an ISO without the SKU for which the MSDM is meant.