Yes Conversations is still a paid app on Play Store. The F-Droid version also doesn’t support Google cloud notifications so some message notifications will go missing occasionally. For Android there’s also Quickly which is a Conversations fork and aTalk which works OK but reminds me of 90s Windows software. It’s still quite usable though. Honestly Conversations is totally worth the money if only for the amount of effort gone into modernising the platform which also a testament to its extensibility.
While I’m not opposed to paying for YouTube (it is a service after all) the only way to do so would be by being logged in to YouTube with whatever black box algorithmic tracking and curation that entails. There is no “proper” way to anonymously access YouTube without ads.