Divide up roles across phones?

I'm a long-time Linux user, but haven't ditched my Google-based phone out of part laziness and part overwhelm-ed-ness. I have read a lot (for years) about the benefits and drawbacks of various deGoogled or non-corporate phones, OS, apps, etc.

However, I haven't really read anyone talk about dividing up their phone experience into segments across a couple of different phones (basically using low-cost carriers like RedPocket). My partner and I are both low phone users already and I dislike having a device with me tracking my every move and selling those data to the AI gods (even from the carrier itself). But I understand I need to access bank and brokerage accounts, 2FA/authenticate for everything (including my account at my local library!). I am also wickedly cheap and like to not spend a lot on tech devices if I can help it.

Is anyone using a phone for basic "gotta have it" apps like banking, home security, 2FA/authenticating, etc. and then using a burner phone for all the rest (texting, phone calls, etc. i.e., not trackable to you per se)? Am I overthinking this?