Why have a compromised phone at all? You're still exposing yourself to telemetry. And if you've ever said anything positive about a Hong Kong democracy activist, you still have to wonder what's going to happen to you if you travel to any country with a mature extradition relationship to China.

I also think it's easy to underestimate your footprint when it comes to ecosystems that involve money in any capacity. No Amazon, Steam, no card information on a Netflix app, no signing in to Google to read a NYT article.

I think either you care about these things categorically or you don't, and I don't think anybody is going to be in the middle space you seem to be envisioning, which is concerned enough about the risks to avoid all banking but still a casual enough attitude about a compromised phone that you're fine with it for uses you consider non-secure.