Try it and report back. I’m genuinely curious to see if it’s what you’re claiming it to be on your end, cause I have yet to see any FOSS Lemmy apps getting triggered in DDG, no matter what links I click. Maybe I’m just lucky?
The biggest alarm in this thread is everyone thinking that apps are at the whim of advertising companies and completely innocent on their part. They are not. Ads can work without trackers and devs can prevent users from being tracked within embedded browsers.
Go to your FF app, Settings, Private Browsing, and enable Open Links in a Private Tab. The bar on the top of the embedded browser in your Lemmy app should turn purple if it works.