I have the ACR ResQLink 400. Can't exactly "recommend" since I haven't used mine (they're single use only), but I researched this a bit before buying.

Just make sure you get one that uses 406Mhz rather than two-way LEO satellites. The two-way stuff requires monthly payments and is far less reliable, won't get through forest canopy. The 406Mhz SARSAT beacons are single use only one-way transmitters (they receive GPS, not 406Mhz-SARSAT, although they still work without a GPS signal). Anything that advertises using it to send SMS messages is junk for emergency use.

There's an older, lower-frequency SARSAT band somewhere in the 150mhz-ish range, but it gets so many false positives (like some ATM in Kansas) that it's basically retired. The 406Mhz protocol has a lot more checksums in it.

Edit: you want this: https://en.m.wikipedia.org/wiki/International_Cospas-Sarsat_...

From some reading I've done, it seems the type of device I'd want is a PLB and not a EPIRB (which you register to a vessel?) It also says PLBs you'd register to yourself and have to update every 2 years - but some articles I've seen say you can use them more than once. (source: https://www.rei.com/learn/expert-advice/personal-locator-bea...) How much of this is accurate?

Also, seeing on https://www.acrartex.com/products/resqlink-400 it says "Battery Replacement: After 5 years or after emergency use, whichever is first"

Well, they both use the same satellites and radio signals. It's the same electronics in different packaging.

Speaking of packaging, the product you linked to is the buoyant version. Don't get that for hiking, it's significantly larger (physically) than the non-buoyant one. Confusingly, they are both called the "ResQLink 400".