In my country almost all (maybe actually all) 2FA services have the option to send a text/sms with a code, that would work for a dumb phone as well. Or via email to your computer. Do you have those options?
I can do banking online without an app, but I want an app for local transport like buses and trains as that is cheaper than paying with card. Are you set to travel without a smart phone?
Other things I use a smart phone for: calendar to remember peoples birthday by. Alarm clock. Photos of my pets being adorable, or injuries to show a doctor or insurance company. Video calls with the veterinarian (a phone is much easier to navigate than a webcam). Digital tickets for movies/shows/events/travel instead of needing a printer. Map and navigation.
Perhaps you can find some sort of dumb smart phone, like for children, that maybe only allows a few apps so you can still have whatever you absolutely need but without mail, browser, etc that tracks and distracts you.
Before making a decision maybe you can try setting up your current phone with a mode (check settings) to only allow clock/alarm, phone, and messaging and see how you manage.