I'm not completely sure I understand what you want to do, I can share some tips.
With FreshRSS you can get the RSS feed of a youtube channel and receive notifications, but YT only gives you the latests 15 or 20 videos, so you won't get older videos, only newer ones.
From this URL https://www.youtube.com/@rossmanngroup
you need to transform it to something like this https://www.youtube.com/feeds/videos.xml?channel_id=UCl2mFZoRqjw_ELax4Yisf6w
You can automate it with an extension in FreshRSS.
Or if you want you can use tubearchivist which will process the channel and download the videos to process them and index them.