Office 365, Google Keep, iCloud notes is the answer.
And Obsidian for the privacy conscious
Obsidian is great for syncing my notes across several devices. It was the major challenge I've struggled with for several years before it.
Are you using the Obsidian subscription/cloud service, or have you made a system to sync directly, e.g., Windows <-> Android platforms?
If the latter, could you share your solution (I took a quick crack at it, but the link structure seems to require nontrivial management?)
TIA
I've used Obsidian Git.
It definnitely takes some set up to make it work, but once working, it is pretty reliable. It requires an occasional merge conflict resolution, and setting the right files to be ignored.
I love that it is just folder with markdown files.