Reminder that on an iPhone, if you hold the Volume Up and Power buttons simultaneously for several seconds, the phone will vibrate and will require the PIN or password next time you unlock it, not Face/TouchID. This happens whether the screen is on or off, so you can discretely do it in your pocket.
I want to use my main mail address everywhere, even public places.
No you don’t. It’s not quite as simple, but buy your own domain, get an email provider such as Fastmail that will let you use a catch-all, then use a unique address for every site you visit.
Then if one starts receiving spam, you can block that specific address and voila, no more spam. Plus you know what sites have either poor customer detail hygiene or are actively selling your details.
Yeah, don’t trust your most critical passwords to a browser when you can instead use a dedicated bit of software designed for saving passwords securely and which will also work on your phone and any other browser you may care to use.