As discussed earlier, Mobile-First Indexing & Desktop Indexing aren’t two different things. If they were, what could be the purpose of prioritizing one as such. Website indexing will remain the same for both mobile-friendly & other UIs. The difference is all about your turn. You need to fetch the Google Search Engine Appearance as soon as possible to start ranking further. And that’s the ultimate rule of the game. No indexing, no SERPs. Google would take more time to index your website pages & even ranking you in the long run.