You cannot link to something that has your personnal contact info. You could always link to your Upwork profile, but it is already linked with your proposal.
You may not give any link to personal contacts in your Upwork profile and portfolio.
However, you may give links to your website or social media in your proposal. That said, if you take work off site, your account will be suspended.
The mods need to answer your question about giving your profile link to a rival site in a proposal. I would think this would be a big no-no.