The strongest SEO angle is spa heat pumps and water-system equipment, where product specifications and sizing can be compared objectively.
What Steam & Oak sells
The current profile lists gas-powered saunas, indoor/outdoor saunas, hot tubs, cold plunge tubs, heat pumps and wellness accessories.
For WaterVerdicts, the most relevant products are hot tubs, cold plunges and spa heat pumps.
Why the heat-pump category is attractive
The site publishes unusually detailed spa heat-pump specifications including output, COP at multiple test conditions, noise, flow, dimensions and operating range.
That creates content opportunities based on engineering and ownership cost rather than vague wellness claims.
Geographic limitation
This is primarily a UK opportunity. Content should be localized accordingly rather than presented as a universal U.S. recommendation.