Need Advice - Monetize Channel with New Content

I have a 200+k sub channel I started many years ago with 1000 videos. Channel has 50 million views. It's educational and all of the videos are documentaries and interviews that I didn't create.

I'd like to pivot to making my own documentaries, so that I can monetize the channel and create original content. I can't monetize the channel for "Reused Content." It would all still be in the same niche. I also have a Patreon and a lot of loyal subscribers.

My question is: Will I have to delete all the old videos to apply for monetization? What effect will that have? Should I upload a bunch of original videos first, delete the old videos, then apply for monetization?

If this was your channel, what do you think would be the best way to pivot this channel to original content and monetize it?

Yes, you will need to delete all the old videos.
Better upload some of original videos firstly, because you will lose a lot of reach after deleting the old ones. So with upload first you will hit 4k Hours watchtime a lot faster on oryginal videos.

Yes, you need to delete all videos. YouTube will review videos even it's privated.

If you are making good money with patreon, just keep earning with it. Post new content on new channel.