How do I check my Office 365 email on the Google Pixel?

Great Question!  The Google Pixel uses the same operating system as most other "non-Apple" or "non-Microsoft" phones, Andriod!  So, the instructions are the same.  Google's own site has a helpful walk-through titled "Add or remove an Account" I have sampled below:

Add an account to your device

1. Open your device's Settings app .
2. Under "Personal," tap Accounts Add account. 
3. Tap the type of account you want to add ...
   • To add a Microsoft Office 365 account, tap Personal (IMAP).
4. Follow the on-screen instructions.

If Google updates their phone's operating system it would be wise to check back with them on how to check mail.  Again, the site may be reached here.