Interesting development in the comments above lol
Anyway, thanks everyone for the help. I am replacing the pump, thermostat, and tank.
If this helps anyone, here are the links (delete the spaces) for all of the OEM cooling system related stuff and where I found it cheapest with shipping:
Reservoir: ht tps://porsche.oempartsonline.com/oem-parts/porsche-reservoir-99610614708
Cap: ht tps://www.fcpeuro.com/products/porsche-radiator-cap-911-boxster-cayman-por-99610644704#fitment
Pump: ht tps://www.fcpeuro.com/products/porsche-engine-water-pump-911-boxster-11243008314#fitment
Low temp thermostat: htt ps://www.fcpeuro.com/products/porsche-thermostat-wahler-99610601359#fitment
Drive belt: ht tps://www.pelicanparts.com/More_Info/99610215168.htm?pn=996-102-151-68-M216&bc=c&SVSVSI=0785#kitsComAnc
Should save you a few hour of googling
