Start everywhere. There are ways to split the stream to multiple platforms using one of the following:

1. A service such as restreaming websites

pros: very easy, lowest computer spec and bandwidth requirements, sometimes has a consolidated chat plugin

cons: sometimes costs money, may have watermark, the service controls the bitrate and has a stream delay

2. Using multiple instances of OBS

pros: free, easy to set up, additionally if you set up an NDI solution over LAN then you can use a multi-PC setup which can be desirable

cons: you will be sending the same data out to multiple platforms yourself, which means you will need high computer specs and high bandwidth or else your bitrate will suffer dramatically

3. Setting up an RTMP server, such as with nginx

pros: free, lower requirements, and low delay. You control the bitrate and everything

cons: many people find this very difficult and often requires troubleshooting

That said, if you're serious about wanting to become a streamer, then where you start doesn't really matter as much as finding a source for views. Views may come from an algorithm, or igniting the passion of a group of people on a forum, or family members willing to watch the entire video in order to boost user engagement, but at the end of the day they do not magically appear for good content: you need to bring them in.

Whatever you do: DO NOT USE SHORT FORM VIDEOS as your primary format. Their audience comes and goes like the tide and they make pretty much no monetization.