Use chrome's "people" feature to segregate AWS profiles. Each "person" in chrome context is a completely separate browser context that that shares nothing.
There's a great plugin that makes managing accounts/roles easier:
https://github.com/tilfin/aws-extend-switch-roles
It lets one control what account/role combinations are visible on the console account/role chooser:

But you're still limited to one login per browser context.
That's where chrome's "people" facility comes in.
One can create a different "person" for every account/role combination.
This means separate and distinct login sessions

The combination of the above plugin and distinct browser people/contexts for each account role combination allows one to map each "person" to a set of role(s) they are expected to use.
Given that each person will lose the context they have if they switch roles, I tend to create only 1 or 2 roles in the plugin config for each person.
So if I want a new account/role combination - create a new person, install the plugin, and setup the plugin to know only about that account/role combination.
This lets you have as many concurrent AWS console sessions as you can keep straight in your head. The "people" feature also lets you pick an identifier icon for each person so you can see at a glance which session(s) you have open.
This shows 4 active chrome canary sessions open, all logged in to different accounts.

Note the circled identifier icons.
eg:
"dev" is a bug
"prod" variants are balls, mnemonic "game day"
etc...
You can also assign a color to each account/role with the plugin. I found that it helps to match the color of the person to that of the account/role, so you can tell at a glance, or when minimized, which it is.
Finally, the reason to use canary is that I want my main "open link" behavior to not use any of these "AWS-specific" browser instances.
This ensures that all my link open in my actual chrome instance and canary is reserved for the proliferation of AWS sessions.
I've seen so many people futz around with opening/closing/re-logging-in/etc that I felt I had to post this as a Q&A.
Hopefully someone finds this useful.