I installed Authy on a rooted phone just to yoink the SendGrid token out and put it in our usual shared authentication service. Such a pain in the ass. I would highly recommend against SendGrid in basically all circumstances fwiw.

Sendgrid was my go to email provider for clients pre-acquisition.

Once they got bought out & forced their poorly implemented 2fa with mobile phone requirements, I had no choice but to find different providers.

Yes, and, if you create a SendGrid account and therefore an Authy account, this may immediately enroll other accounts of yours on entirely unrelated websites/services/platforms into Authy, presumably by correlating your phone number. (Even if the email address is different!) This includes big sites like Twitch, and also includes sites where you had selected the "only allow 2FA via security keys" option. Of course some of the blame here probably falls on those platforms, but both the fact that this is possible and the fact that Twilio encourages these patterns are reprehensible.

Yeah. I have always wondered what they gain by doing this.