[smokel]

Do you swap SIM cards all the time? This seems to be the biggest blocking issue for me.

I tried switching phones once a week, which was heavenly. Might try that again, it requires some discipline.

[mrweasel]

Apparently some phone companies can/will provide you with aux SIMs, which allows two phone to share a number, or so I've been lead to believe. I can't find a single provider here in Denmark that will issue me such a SIM. Kinda sad about that, because it would solve most of my issues.

I need a smartphone for a few things every so often, but most of the time a dumb phone is perfectly fine.

[tristanj]

I do not, the gym phone has its own SIM. I have it running a cheap data-only eSIM from esimdb.com

If you need synchronized phone / text messages, I suggest Google Voice. When anyone rings your (free) Google Voice number, it will forward the call to multiple phone numbers. It will ring as a regular phone call, not as an app notification. However, text messages appear as app notifications.