Perhaps I’m you guys’ worst nightmare, but for the past couple of years I’ve been writing haikus for my OOO, which give a flavour of what I’m out doing. A couple of examples:
We had someone at my old job whose auto-reply stated that they were at a “White Privilege Conference”. Granted, the conference was about dismantling White Privilege, but to someone outside our work who didn’t know that, I imagine that got quite the reaction!

Yeah, announcing you were going to delete emails unread and expecting the sender to resend when you return would NEVER fly in my office. I’d get executive complaints about that, especially if it went to a client or outside party – if a client can’t reach you, they will reach out to someone else who may not work at your organization and you lose business. I feel like this delete-it-all philosophy would only work for an entirely internal role where timelines are more relaxed, and even then, I feel it’s a bit unprofessional to foist your own catch-up work onto others, especially if they’ve been backfilling for you while you were OOO.
We are encouraged to put up messages that say we have “limited access to email” and alternative contact for things like travel between offices and conferences. We’re technically working those days, but it may be hard to reach us.