Or use some JS to put the time-on-page in the next request, right? Is it a violation to send data that could theoretically be used for more invasive tracking t

Or use some JS to put the time-on-page in the next request, right? Is it a violation to send data that could theoretically be used for more invasive tracking than you actually do? I don't think so, or else you'd need consent just to receive an IP packet.