Even as my use of Obsidian grows daily, I am still finding Obsidian mobile totally unusable.
But… having said that, the fact that the vault consists of folders of markdown files means there are alternative solutions.
One of the most common use cases for mobile, is to take a quick note. iAWriter (other markdown editors as well) is ideal for this. If I want to save an image to the vault I simply download it and copy to the vault. I can share (Android) URLs to my file manger and they will be stored in text files that can be later renamed as markdown files. Otter (https://otter.ai/) works well for voice to text and its its files can be exported to iAWriter and saved as markdown files. As a heavy user of the Excalidraw plugin, being forced to use Squid (https://www.squidnotes.com/) for sketches is far from ideal, but at least I can share sketches to the vault as .pdfs or .pngs. The web version of Excalidraw is another possibility but seems too much fiddling around to save and import into the Excalidraw plugin.
For me this hybrid solution works well and I am close to uninstalling Obsidian mobile.
I know Joplin is another option that would leverage markdown, but seems too much effort to learn two note taking apps, especially when I already have all the other apps I mentioned.
Fortunately, there is a Llinux (as opposed to Android) option for ChromeOS. I installed Obsidian using Flatpak/Flathub and it works really well. This might be an option for those wanting to use Obsidian on a tablet. But pay attention to the Chromebook spec, mine is an i7 with generous RAM and the performance is very acceptable.