No SYSTEM can be "GAAP-compliant", but some work better than others to meet GAAP compliance.

GAAP (Generally Accepted Accounting Principles) are accounting practices that accountants follow, not anything that the software does for you.  One part of GAAP is requirement for accrual-basis accounting.

QB and QBO are both cash-basis systems, so to follow GAAP you must work around system defaults and skip some of the automated functions that are all cash-basis, such as posting expenses from bank feeds.  

Note:

Accounting is done on cash or accrual-basis.

Income taxes are done on cash or accrual-basis. 

These are two different decisions that a company makes and they do not have to be the same.

Meaning is the same for accounting or taxes, cash-basis are only transactions where cash is exchanged.

There are 10 GAAP Principles, which include accrual-basis accounting. (Tax is a separate decision to make).

GAAP are accounting practices performed by an accountant not a system so no accounting software can  "approved" as GAAP compliant.  That is like saying a car is approved for no accidents, not possible since any car be in an accident, only the driver can have or not have accidents in the car.