my needs are more utilitarian - I need a smart phone that's waterproof. Not a single one of the libre* phones are waterproof, let alone reasonably water resistant, so they're a nonstarter for me. I'm a nerd but I'm also outdoorsy. My phones have gone for swims in the Gulf of Mexico and been caught in squals more times than I can count.

My experience is that water proof phones ironically are more prone to water damage since they don't drain. Simple moist in a tent can kill it.

Can you give examples from your experience?

My current phone, Samsung S9, got ruined in a moist tent. It said "water in charging port" and refused to charge since that point. Samsung fixed on warranty.

My wifes prior phone got cracks on it and it seemed to let in moist and then not drain or get dry. Something fried in it.

I had an S7 for years, and then upgraded to an S10e. I was just in a pool yesterday with the S10e taking video. The charging port message is to prevent damage. If the message never goes away or you have intrusion, that's a valid warranty claim.

Doesn't that rule out any phone?

Not, reportedly, the Librem 5 phone.

But it still contains a cellular modem and a wifi module, both of which run proprietary firmwares.

But, crucially, they both run externally to the CPU and main system, and can not affect it in any way. It’s just as if they had put the firmware on a ROM chip beside the modem and wifi chip.

A phone, sure, a smartphone, not a chance

The Librem 5 is absolutely a smartphone: https://puri.sm/products/librem-5/

Your linked page calls it a "phone" not a "smartphone", so you're proving GP's point.

What. By that definition, the Google Pixel 5a is not a “smartphone” either, since its product page does not use that term, either: https://store.google.com/us/product/pixel_5a_5g?hl=en-US

Your leg is being pulled.

*plonk*

By what metric is it somehow not a smartphone?