New to KP. Best way to backup to cloud? .kdbx & keyfile in different clouds is best?

Started using Keepass Portable recently with version 2.57 and now I'm on version 2.59

I have this structure:

🟦 mydatabase.kdbx 🟦 mykeyfile.key

I have multiple backups of the entire Portable folder in zipped password protects files.

2 X backups on two phones
1 X backup on PC

I want to now backup to cloud.

1. Which cloud service to use
2. Upload kdbx to cloud and leave .key locally?
3. Upload kdbx & keyfile to diff clouds?

What system do you all use for backup. Do please share.

Thanks for your advice and for your time.