The keyboard layouts used in macOS work in every Mac, with any hardware keyboard attached.
In other words: How you see your custom keyboard layout displayed in Ukelele doesn’t affect its workings after you’ve installed it.
It’s only a View.
Still, for convenient editing, Ukelele has a list of possible hardware layouts you can choose from.
Type Cmd-K to get that list, or open the View menu and click the option Keyboard Type:
The most important choice in that dialog is in fact not the keyboard model, but the "Coding" seen on the right:
After finding the type and coding best matching your hardware keyboard, you can make them the default in Ukelele > Preferences.
You can read more about that in the PDF manual (available through Ukelele’s Help menu), in the first 4 paragraphs of section 6.4.2 on page 25.
The preferences: 8.2.1 on page 63.
Or read the full story in Sections 9.1 and 9.2 on page 78–79.