can I back up my apple watch to a computer or other device if I lost my iphone?

ohwell-17 wrote:

Can I back up my apple watch to a computer or other device if I lost my iphone?

No. An iPhone is required.

You can unpair without the iPhone, and re-pair to a different iPhone.

Unpair and erase your Apple Watch - Apple Support

Any iPhone backups made prior to the loss—whether to iCloud or to a local Mac or Windows system—contain your Watch backups.

If you are using the cloud backup it is in there every time you backup your iPhone.

You can’t backup your watch alone.