Possible to allow setting of UseCookies property in JsonHttpClient?

Doesn’t look like it works by default, (very little does as it’s primarily a wrapper around W3C fetch API), but this answer suggests you can set a switch to toggle the underlying fetch() to use credentials: 'include':

The solution is to use an HttpRequestMessage and set requestMessage.SetBrowserRequestCredentials(BrowserRequestCredentials.Include);

Which you could initialize with a static global Request Filter, e.g:

JsonHttpClient.GlobalRequestFilter = req => 
    req.SetBrowserRequestCredentials(BrowserRequestCredentials.Include);

Note this API is limited to Blazor package.