I have been using an iPad Pro as my primary computing device for more than a year now. It works pretty wonderfully for my use case. I just finished writing my dissertation on it last week, actually. I have an old MacBook that I use for specific tasks once or twice a week, but otherwise my iPad, pencil, and keyboard/mouse/5k monitor on my desk works really, really well — better than a laptop by far for my workflow: Zotero/Markdown/MSWord/Logseq/Obsidian.
I’m very happy to not use a general purpose computer anymore, to be honest.