For a new app I'm working on, I needed to display a measurement in a SwiftUI Text view with the unit in a smaller font than the value. We can do this by targeting the unit component in an AttributedString. I shared an example on my blog: https://nilcoalescing.com/blog/StylingMeasurementUnitFontsInSwiftUI/
Styling measurement unit fonts in SwiftUI

Use the AttributedString API to build a reusable Text initializer that applies a distinct font to the unit component of a formatted measurement.

Nil Coalescing
@natpanferova I do something similar in my app