The Gmail App

I use it for work + 2 of my Gmail accounts and no issues.

Define unusable what are you experiencing?
 
I use both Gmail and Microsoft Outlook with my Pixel 6 Pro on Google Fi.
Everything works problem free here.
 
If Gmail is bother you switch to Outlook, far superior IMO.

No unified inbox on Outlook. That's what kills it for me. I have several email accounts and rely on the unified inbox. Gmail's iteration is not perfect - you cannot choose the unified inbox as your default display. But you can show it with a couple taps to the screen.
 
No unified inbox on Outlook. That's what kills it for me. I have several email accounts and rely on the unified inbox. Gmail's iteration is not perfect - you cannot choose the unified inbox as your default display. But you can show it with a couple taps to the screen.

Are you referring to an inbox that shows emails from all accounts?
That is the default view in outlook.
When I open outlook I see emails from all 3 of my accounts (one is a work account).
Also the focused inbox is very handy putting most of the important emails front and center.
 
I was using Outlook for Mac. Perhaps that's the difference. Or maybe they've added it now. I'll have to give Outlook a go on my Pixel 5.
 
If Gmail is bother you switch to Outlook, far superior IMO.
This! I hate GMAIL and how it marks emails as important as it pleases then I have to delete old emails both from the inbox and again from the important emails it like creates a duplicate of each.