MyViewModel.kt

// Get the registration options from the auth server

suspend fun getPasskeyRegisterRequestJson(username: String): String
    = withContext(Dispatchers.IO) {
        val url = HttpUrl.Builder()
            .scheme("https")
            .host("auth.tomcolvin.co.uk")
            .addPathSegment("generate-registration-options")
            .addQueryParameter("username", username)
            .build()
        val request = Request.Builder()
            .url(url)
            .build()

        val response = okHttpClient.newCall(request).execute()
        response.body?.string() ?: throw Exception("No response body")
    }