AvaloniaUI or Blazor Hybrid ?

We have a small app where I work and I want to rewrite it using one of the two methods listed above.
Let's say I know C# pretty well, but I did backend stuff (web APIs, microservices etc).

AvaloniaUI seem like the obvious as it is suited for applications written in .net.

On the other hand, Learning Blazor seem more beneficial as I will be able to use the knowledge I will acquire even further later on (we have admin tool written in silverlight where I also want to rewrite).

My question is, how different is Blazor Hybrid from normal Blazor (Blazor server/Blazor webAssembly) ?
Is the UI in Blazor Hybrid is also in html/css ?