MISRA is there as a standard for safety-critical code. Some contracts, some customers, some regulatory regimes will require compliance with MISRA, or perhaps another embedded coding standard, like AUTOSAR.

Generally, your customer/regulator will allow you to deviate from the standard; you just need to document and explain the deviations.

A static analysis tool like Helix QAC or Klocwork (bias: my company Perforce sells them) will capture your compilation and scan your code in detail to find deviations from the standard. You can then fix those deviations, or use the tool to document and explain them.