I've also been in situations where an ultimatum like E2E encryption is dictated by a marketing team and then expected to be created without adequate budgeting or time, essentially creating pressures on development teams, project/product managers, etc to lie.
The conclusion I've come to in business is that ultimately, your product or service is going to be falsely advertised and oversold one way or another. It's a lot easier for some to lie, act deceitful, and/or feign ignorance than it is to actually deliver. Your competitors are doing it, if you don't, you lose.
The way I deal with this nonsense is that I make it a point at least once in meeting or fairly tracable record like an email that others know what is and isn't true once and it's up to them to decide who they want to lie to. I've been on the other side being pressured to lie and its not fun so I'll happily pass that responsibility. I didn't pursue a career in computing to be a constant liar, I'll let the people who want to lie, lie.