For those like myself who used Bartender as a way to get an extra menu bar for their offscreen items on small / notch screens (something Ice doesn't have yet), I'm writing up the alternatives as I try them out:
https://procrastopossum.com/bartender-alternatives/
So far I'm just hoping the BetterTouchTool option pans out.
It's by Vladimir Heiskanen. His blog hasn't been updated in a long time, but has articles explaining some of the principles behind red light therapy: http://valtsus.blogspot.com/
I don't know of a device that can measure it at home, but there are mail-in saliva cortisol kits from companies like Genova Diagnostics, Labrix, and ZRT Labs. You usually send them several samples collected at specific times throughout the day.
They're mostly designed to be ordered by a healthcare professional, but you can get a few of them direct on Amazon, or through companies that order on your behalf (similar to healthlabs.com mentioned above).
Choice of Quest or DirectLabs: Walk-in Lab (switch the radio button to Quest on the category pages, and make sure a "QD" icon shows up next to it in your cart), TrueHealthLabs (make sure the tests you look at say Quest is an option), HealthTestsDirect (make sure the test list page is toggled to Quest at the top)
DirectLabs and Walk-in are generally cheaper than the others I mentioned.
I've tried DirectLabs, WalkInLabs, and Life Extension, and have been happy with them all. All of those companies are basically just "doctor ordering resellers" for the two big test labs (LabCorp and Quest), so you generally don't have to worry about the quality of the testing.
I specifically use Life Extension for vitamin D because they're the cheapest one I'm aware of.
The key words would be to ask for an "iron panel". In most US states you can also order one yourself without a doctor's visit, but without much option of having insurance cover it.
For those unfamiliar with Upspin (as I was):
"Upspin provides a global name space to name all your files. Given an Upspin name, a file can be shared securely, copied efficiently without “download” and “upload”, and accessed from anywhere that has a network connection."
https://upspin.io/doc/overview.md