Or just use a standalone device with a hard power switch, that doesn’t tether to your phone. My wife and I have a tiny little ESP32 mesh texting+location devices for when we’re in crowds where the cellular spectrum will be saturated, or where the reception is typically just shit. But they stay off unless we’re actively using them (like when we’re separated in the crowd).

If we go to a weekend festival, we just charge them before we leave and then they easily last all weekend. Because we’re only really using them as temporary beacon system to find our way back to each other.