If you care about this stuff you need to in-house auditing and do your own audits with people who care. Then get certified by an external auditor for the paper.
You can start very lightweight with doing spec driven development with the help of AI if you're at a size where you can't afford that. It's better than nothing.
But the important part is you, as a company, should inherently care.
If you rely on an auditor feedback loop to get compliant you've already lost.
To be honest, I would even go further: if you think certification equals security, you are even more lost.
So many controls are dubious, sometimes even actively harmful for some set-ups/situations.
And even moreso, it's also perfectly feasible to pass the gates with a burning pile of trash.
But companies don't care. They don't want compliance for feel goods, they want compliance because their partners require it. They do the minimum amount required to check the box
This function exists in every publicly traded public company, and is called internal audit.
It has the potential to be incredibly impactful, but often devolves into box ticking (like many compliance functions).
And it's really hard to find technical people to do the work, as it's generally perceived as a cost centre so tends not to get budget.