I downloaded the DEB-package vivaldi-stable_1.12.955.36-1_amd64.deb from
https://vivaldi.com/download/ and let ''sce-deb2sce'' run over it. The resulting extension I put under '/tce/sce/'. Loading the extension does work but there is no executable found. Upon further inspection I found that the loaded SquashFS does not have its permissions set right under '/tmp/tcloop/':
drwx------ 6 root root 71 Sep 27 16:30 vivaldi-stable_1.12.955.36-1_amd64/
Checking as root user, there is a symlink in the SquashFS from 'usr/bin/vivaldi-stable' to the executable 'opt/vivaldi/vivaldi'. AFAICT sce-load should make this available indepently of the specific case of software. The behavior is reproducible on another system, both machines running dCore-xenial:2017.09.24.21.13. Therefore I suspect a bug in sce-deb2sce. Can anybody verify?
PS: I just realized that I should not use the 64-bit version in dCore but that wouldn't affect the behavior of sce-deb2sce as far as linking the SquashFS.