I currently use Lightroom Classic to manage my approx. 100K pictures (800GB). I use my laptop to import, sort and organize files from my SD cards in LR classic. From time to time, I move these files from my desktop to an external hard drive. Thanks to LR, I can keep working with the thumbnails and keep hard drive space on my laptop, even when the external hard drive is not connected. My current plan comes with 1TB Adobe cloud space I would like to somehow incorporate it into my workflow to work with and/or backup my photos.
I read you can upload everything to CC and create a copy to an external drive. Sounds hands off and easy to me, plus would give me a backup in case my external drive fails (currently my biggest concern)
Lightroom stores your original photos in the cloud, and comes with built-in backups of all photos (assuming it doesn't take more than 1 TB in your case), and you don't have to do anything to obtain this backup in the cloud.
The trick is getting Lightroom Classic and Lightroom to work nicely together, and I leave that up to others to explain.
The Adobe cloud shouldn't be regarded as a backup system. It is an active tool for making images available across all your devices to enable editing and sharing those images. But it isn't someething to be considered as your backup. You might consider other cloud services such as Google Drive, for instance. That is just one suggestion.
You apparently have only a partial understanding of what the Adobe cloud is all about and how it integrates with the Adobe ecosystem. It's a rather broad Topic to try to explaiin on a forum. You could do some searching on YouTube. Search carefully because Adobe has created a lot of confusion by naming Lightroom as they did, confusing it with Lightroom Classic.