@lonm Not quite (at least not in the sense of being like a filezilla clone) but I think I can see where you're coming from.
In this suggestion, Vivaldi has a secure enclave of creds. You visit the web site and right click on the file to download and choose your remote system as the target (with the option of choosing a destination directory) and click download. Vivaldi then creates a ssh shell equivalent and then runs a wget like command on the remote host.
I acknowledge that Carte Blanche command execution is a bad thing which is why this feature on the remote resource side would be intentionally restricted.
The idea is to provide the functionality of the browser as if you were running it locally on the remote resource with some added sugar like automatic checksum checking and that sort of thing.