The 60.4g one is here. It has a 2.45 inch screen, 1100mah removable battery, has been around for a while, and runs Android 8.1. By its dimensions it MIGHT fit into an Altoids tin (which would of course block RF signals from reaching it, good or bad depending). I emailed the company and they replied there are no plans to update it, unfortunately. They have a newer "Jelly Star" version that runs Android 13 and has more features, but is 2x as heavy. I suspect the lighter one didn't catch on because the battery was too small, but it might be ok if you don't actually use the phone much.
The 560g version is here. It is that heavy because it has a 22000mah(!) non-removable battery. It also has a built-in 1200 lumen flashlight, 6.81" screen, accepts 65 watts USB PD fast charge, and generally looks like a capable modern (8gb ram, Android 12) phone, though it is 4g only. They do have some 5g models that are smaller.
Why is a 560g phone ultralight? Well on Reddit r/ultralight they always talk about power banks, and the lightest 20000mah power bank is around 300g and it is popular there. This thing combines the power bank and a phone, so saves the weight of a separate phone. They also like to spend days on the trail and then duck into a restaurant for a recharge, so they like fast charging. Most phones and power banks recharge at 15 watts so you don't get that much in an hour, even with separate chargers for your phone and PB (i.e. 30 watts using both at once). This thing supposedly takes an almost full charge in under 2 hours. Finally, it is good to get rid of the cable between the power bank and the phone. Not for weight (you still need to bring a cable) but because USB connectors are way too fiddly and they break all the time. So the less often you plug and unplug a phone, the better. Huge batteries from that perspective are good.
I should also mention, the above is supposedly a ruggedized phone. If that means you don't need an add-on protective case, that saves some more weight.
I have never used or seen either of these phones (just heard about them last night) and don't feel likely to buy one (especially the Tank), but both are interesting enough that I thought I'd post here.
Update: there is an even bigger (666g, 31mm thick) follow-on with Android 13, 5G radio, 16GB ram, and 120 watt charging: https://liliputing.com/unihertz-tank-3-smartphone-has-a-23800-mah-battery/
In addition to the rather antiquated OS version, you can count on the Unihertz Jelly probably not working on 4G with your chosen cell carrier in the US in most locations. If all you want it for is to hold maps and play music, maybe, but this thing supports precious few of the 4G LTE bands used in the US, even in its "US" variant (according to the spec page, anyway). As 3G service is progressively shut off to make room on the spectrum for 5G, you can count on it getting even more useless over time for voice and text as well. It's also micro USB, so if you've transitioned all of your other gizmoes to USB-C you're going to have to tote around another cable.
Hmm oh well, that is interesting, thanks. I have been thinking of getting one mostly for use as a 2FA token since I don't want my 2FA credentials on my main phone which also has stored passwords. Having both on the same phone isn't two factors of course. But it would also be nice to be able to use it as a backup phone. The 2.4" screen isn't that great for maps.
3G in my area is dead and I had to go berserk trying to update my old phone to work with 4G and it has been a bit messed up since then, one of the reasons I'm looking for a new phone.
Does the Tank also have limitations on its 4G bands?
Do you think it is worth getting a 5G phone instead of 4G if I don't really care about increased data speed? I mostly care about whether it would work in more places. I'm looking at the 4G vs 5G versions of the Motorola G Stylus if that matters.
I find myself interested in the Tank partly for those Crocodile Dundee moments where I can pull it out and say "that's not a phone, THAT's a phone". ;)
The larger phone lists more frequencies, but I didn't exhaustively research if it has the right bands to get good overlap with US carriers.
If you can, 5G is the way to go. There is no new development on 4G and few to no new 4G towers are being installed at this point. Coverage on 4G will only get worse over time, and 5G coverage is already better in most parts of the country. It'll be the same story with 4G in a few years as it already is with 3G which is now useless or nearly useless as carriers are not widely supporting it anymore and some carriers having already dropped it entirely.
Thanks! I picked up the 5G Motorola yesterday. Had to uninstall a lot of bloatware and unset a lot of privacy invasion switches, but I do like the phone.