So I gotta be honest I'm on the newer side of things. More of a programmer than SEO, but... anyways

A "business coach" wants to potentially work with me on building their brand and website.

She's got a bunch of experience managing nurses, including high stress areas (war zones)

I'm looking at Ahrefs for keyword ideas and kinda not coming up with much that has a lot of searches...

As I understand, blogging isn't just about search volume, and was thinking of just suggesting to blog comprehensively about her niche, and to just leverage those posts to establish trust and build relationships.

Anyways, I was wondering if anyone has any suggestions on how to approach this?

I don't see any good competitors to steal ideas from unless it's places like Tony Robbins site.

Just focus on the buyer persona and build around that and not worry about search volume?