The one thing that didn't work well was Location services when my wife and I travelled to Walt Disney World. The My Disney Experience app worked great for the most part, but occasionally I would get errors related Location claiming that I was outside of the country. Uber worked fine though. Fortunately we were travelling together and had her phone to fall back on when we needed it.
Besides, GrapheneOS already supports the native Google Play Services (with additional sandboxing), so I have a hard time seeing how MicroG would help here. (I used MicroG on LineageOS for years and it certainly wasn't without bugs.)
Also, regarding what GP wrote, I haven't encountered a single app in a long time that wouldn't run on GrapheneOS.
In Norway practically any place that accept cards also accept Google/Apple pay - as all pos terminals support "tap"/NFC as does practically all debit/credit cards issued here.
I was recently on vacation in France - and only needed my phone there as well.
> Do you not carry a wallet?
No. [Ed: no longer, no]
> What happens if your phone dies?
Either I don't buy anything - or I'd borrow a usb-c charger from the person behind the bar/at the restaurant etc.
I can see how this could be a deal breaker for some.
Speaking only for myself, personally, I'm 42 years-old and have been a very slow adopter of smart phones in general. GrapheneOS let me feel like it's finally my phone and I've started using it more. Mostly as an mp3 player while exercising, and I've got an open source password manager that I've started using a lot. But I've never been comfortable with the idea of my phone replacing my wallet. I mean, sure it can do everything that my wallet can do but it's also susceptible to malware or attack and if I lose it then not only do I lose all of the data on my phone but I lose access to my identification and payment methods as well? That is a terrifying prospect to me. I don't like the idea of single points of failure. Losing my wallet would ruin my day. Losing my phone would suck but nothing catastrophic would happen. For most people losing both would be a nightmare scenario.
But I don't even do online banking on my phone. I probably could. I choose not to.
National/Banking id/2fa would be a deal breaker probably - all infrastructure is built around smartphone apps now - and it's a challenge to find an alternative (ie hardware token issued by the bank).
There nominally is a national id system with printed 2fa codes - but my impression is that it is fading in favour of the banking id system. Except for a few government services like social security, where it remains a viable alternative.
For online payments, with a credit/debit card the banking id 2fa system is practically required to spend money online.
So basically it's a situation where you need the smartphone anyway, but wallet is optional.