You have to ask yourself: what can you actually get away with.

If you’re techy, get a Linux phone. I assume there’s a WhatsApp client, but if not you could bridge to Matrix.

Then you’ll have the option to use a phone, without the addictive qualities of Android/iOS.

Your next best will be GrapheneOS. By default, no Google, so no notifications at all. But that can be turned on and enabled if needed.