Everything will not work perfectly. Let's be honest here. Look it up, some banking apps work mine doesn't. Pay will work one day and not the next. And if your bank finds out your account was hacked and your phone is unlocked and/or bypasses bank security protocols who will pay for the missing funds when they find out?
A missing device can be booted into a custom recovery and adb commands will be available to take everything on your device bypassing any security you have. With a locked bootloader that is not possible. So if you know your phone can be compromised you feel more secure? That is ludicrous and really doesn't make sense. I mean talk about smoke and mirrors.
Now that being said there are a lot of folks in your camp that say you're living a pipe dream if you think the phone is more easily hacked or info stolen. I understand that argument entirely and it's possibly correct to a certain degree. But to summarily say immediately unlock your bootloader if you don't plan on rooting because.. well just in case, is really disingenuous to a great many individuals. At the very least look up some articles on why to keep your bootloader locked, especially for someone that hasn't done it in some time, if ever. The beauty of Android is the possibility if you so desire. Just be conscience of the advice you give. Many years ago Chainfire said in his blog that if you have an unlocked bootloader and have financial apps on your device you're asking for trouble and you might want to rethink that. (not in so many words) That weekend I locked my bootloader and never looked back. I haven't missed anything.. well other than flashing MVK kernel for my 6a. ;-) But then I'd need root and that brings a host of other issues.
You're thinking about hacked non-pixels. None of what you've said applies.