yes you can submit a different address in PR Confirmation Portal. No issues but before putting new address Please make sure the address is as it is at it appears in Canada post directory here : https://www.canadapost-postescanada.ca/info/mc/personal/postalcode/fpc.jsf
This will save you some time & doing back & forth with IRCC.
Also a quick tip : in case they delay in sending you PR Portal Credential email try spamming their mail by replying to the first PR Confirmation Portal e-mail every day twice. Reason as this is their common mail box so everyday many people reply to same email so for you to be on top to get noticed by the officer you need to spam them daily. I did it & it works.
Thanks
Thank you very much for clarifying the subject and for your tips! Very helpful.