I now can't decide whether to leave this tab open as a reminder for me to implement open tabs vs time graph. Rather than run a server on my machine, I'd prefer a tiny extension that sent an updated count to a service every time I open or close a tab. The easiest service to use would probably be a google sheet.
I use https://chrome.google.com/webstore/detail/quick-tabs/jnjfein... to let me search through my tabs across different windows etc. and it tells me I have 320 open at the moment in my work profile and 56 in my personal profile.