As you can see favicon is in the wwwroot folder:
On this page:
https://www.daveabrock.com/2020/11/08/blast-off-blazor-update-head/
There is a content:
Now, we can head over the RealFaviconGenerator site to upload our new icon. After adjusting any settings to our liking, it’ll give us a bunch of icons, which we’ll unzip to the root of our wwwroot directory.
In index.html in the wwwroot directory, add the following inside the <head> tag:
<link rel="apple-touch-icon" sizes="76x76" href="/apple-touch-icon.png">
<link rel="icon" type="image/png" sizes="32x32" href="/favicon-32x32.png">
<link rel="icon" type="image/png" sizes="16x16" href="/favicon-16x16.png">
<link rel="manifest" href="/site.webmanifest">
<link rel="mask-icon" href="/safari-pinned-tab.svg" color="#5bbad5">
<meta name="msapplication-TileColor" content="#da532c">
<meta name="theme-color" content="#ffffff">
Do you mean this?
If not, can you explain?