Important to say, I mean products you use even though there are alternatives, not monopolies like YouTube.
I don’t think this is quite true when it comes to YouTube. There are plenty of alternatives that content creators could use (and some do), from Vimeo to Nebula to PeerTube.
The reason content creators prefer to upload on YouTube are the user base and monetization opportunities. They’re not forced to do so, and in fact YouTube is facing competition from e.g. Twitch and TikTok.
Others already gave some good suggestions, but if you want to keep using your computer, another option could be a second display and a drawing tablet (e.g. Wacom)