I've spent weeks looking for the perfect feature phone and this is my experience:

I just needed two things: WhatsApp and calls.

The most recurring names in my researches were:

• CAT s22 flip: Too expensive and the interface is too smartphone-ish.
• A few Nokia models (3210 4G, 2660 Flip 4G, 235 4G): KaiOS based, they don't support WhatsApp anymore.
• Japanese models (e.g. Samsung Galaxy Folder 2): Not available on Amazon in Italy and didn't wanna get a used model because I wanted to be free to return it in case it wasn't the right fit for me.
• Xiaomi Qin F22 Pro: Same problem of the previous point.

I was about to lose any hope when I found the TTfone 970 on Amazon (didn't know the brand until that moment).

Pros

• The UI is minimal and intuitive.
• WhatsApp and Aurora Store support (both pre-installed).
• Touch screen (the phone is fully usable from the physical keyboard though).
• Exporting contacts from a smartphone and importing in the 970 via bluetooth is straightforward.
• Starred contacts can be set to receive calls even when Do Not Disturb mode is on.

Cons

• The hardware quality is pretty poor, the flip screen slightly wiggles when it's closed and you can hear some creaks by pressing the sides or the back (this also makes me question the long-term durability).
• Poor customizability (e.g. the position of the apps in the home screen can't be changed).
• Battery life isn't great, you can get one full day with it with a basic usage but I'd expect something more from such a simple device.
• If you wanna use WhatsApp on the 970 as the main device and connecting a secondary one (e.g. WhatsApp web on a pc) you can't use the qr code method because of the poor quality of the camera. To do so instead you can use the phone number method but that comes with a problem too: there's a bug that doesn't allow you to insert the code received from the pc because the input field is recognized by the default keyboard as a number input (while the code actually contains both numbers and letters). The good news is that you can install Gboard from Aurora Store and temporarily set it as the default input method, this way you can use a full digital querty keyboard through the touchscreen and bypass the problem.

Then I also found out that Saiet (another unknown brand until that point) has a model called Saiet LINK 4 Pro that is almost the same device and It's available on Amazon, so I tried it and this is what I found:

Pros

• All the 970 pros are also valid for the Saiet but the latter sits on a whole different level in terms of build quality. It's waterproof and shock resistant and has a really nice to the touch matte finish, the flip mechanism is really solid and there are no wiggles at all.
• The screen and the speaker are slightly better.
• The general smoothness of the OS feels better.

Cons

• All the other cons apart from the build quality are valid for the Saiet too.
• The battery life is even worse than the 970. To overcome this I opted for an always-on energy saving mode that allows a longer lasting battery life but with the drawback of not receiving WhatsApp messages when WhatsApp is closed. For my kind of usage this is not a problem because it forces me into an even deeper detox experience but it could be a pretty annoying problem for someone else.
• I can't find the "set as favourite" option for the contacts, so the Do Not Disturb mode is not a perfect fit for my kind of usage.
• The Saiet is heavier and somewhat thicker.
• A bit more expensive (140€ vs 110€).

In conclusion I chose to return the TTfone 970 and keep the Saiet as my main device and, even if there's space for improvement, it's a pretty good fit for me.