I use an iPhone with Obsidian mobile as well as a pc for Obsidian Desktop. I do use Obsidian sync. One relatively small thing that I have struggled with is syncing notes that have characters in their name that are legal on iOS but illegal on Windows. These occur for me as the result of using the Obsidian webclipper bookmarklet for Safari - Obsidian Web Clipper Bookmarklet with full Markdown support for images, headings, and code blocks - #53 by I-d-as. While this is not totally relevant to the question, it is something to consider when getting a phone. As a side note: Copy Sync Log command to respect Errors Only (related feature request for the issue I mentioned).
Good luck!