Microsoft, unfortunately, threw in the proverbial towel with its Ad Monetization platform for UWP apps. While we are waiting for a more official and detailed statement and suggested transition path, what are the alternative advertising networks available for UWP we can use?
Vungle
Vungle is an established mobile advertising company with a name which is a play on the word "jungle". It offers SDKs for all mobile platforms, including UWP.
Vungle offers multiple advertising formats, including full screen interstitial and rewarded ads.
The SDK is available on NuGet and samples are available on GitHub. You can also find documentation on the Vungle website. You can sign up for Vungle here.
AdDuplex
AdDuplex is the leading user acquisition platform for Windows, founded by Alan Mendelevich. It offers free cross-promotion of your applications. It is very simple - by providing advertising space in your application you promote applications of other registered developers, who in turn promote your application in their apps.
Integrating AdDuplex is effortless and offers two different ad unit types - banner and interstitial.
You can sign up and try out AdDuplex here for free.
Pubfinity
Pubfinity is an advertising network targeting Windows applications, which is currently in invite-only beta. I haven't been able to try out this network yet, but I have heard there are already some apps which integrated it.
If you have any further information about this network, please share it in the comments!
Summary
There are currently two open advertising networks available for UWP apps and one in private beta. I sincerely hope that Microsoft has a plan to help other advertising companies get on board with Windows apps, for example AdMob or MoPub. Both mentioned networks already have cross-platform mobile support, so adding UWP could be a nice expansion of their portfolio, especially with WinUI 3 on the horizon.