Slack will work, all chat apps will. Banking Apps can be an issue as Google pushes for their device attestation solutions (“PlayIntegrity”), it’s a bit of a cat+mouse game for that category. As with that 2fa auth app I can’t test fully without an account to fill in, but it’s available and starts, I’d expect it to work.
Hard to say if /e/OS is mainstream ready, rule of thumb is some sacrifices need to be made, checkout FP6 tagged posts. Apple will always have higher polish and deep integration. Are you motivated to go through migration docs?
In the forum we don’t see the silent group where everything works out for their needs. Technical users can install it on some older secondhand Pixel to trial before buying new / from the store to see if it’s for them.