You can execute a bash script as your Build Command, e.g. "./pages-build.sh" which would need to be included in your repo. Within this script, you can install dependencies for an Ubuntu-based system.

Here's a great example someone wrote up for Blazor (wasm) on Pages specifically: https://swimburger.net/blog/dotnet/how-to-deploy-blazor-weba...

Oh... so you're talking about build-time dependencies?