Not really a enhancement request. But just a FYI. I updated vscode-angular-html, and it now doesn't use all the previously matches scopes. It uses different ones, and has a feature that allows you to customize the desired colors as you want, or set the legacy colors. I have documented every scope change here.
I will regardless of that, I'll add support for your themes via the Set Legacy Colors customizations command. Thanks for supporting my extension :)