i have the vivaldi and fedora repositories for dnf. can i assume that downloads from the repositories have md5sum/hashsum/checksum? what about integration with other app stores that have verification natively? can someone write a verification extension like TAILS has? am i missing something that makes my questions redundant?
Fetch your package from Vivaldi original download site.
You don't need a extra checksum. The downloaded packages are internally GPG signed and have shasums of all include files.
If you install the package with your package manager all sig and shasum are checked.
is that true for windows, rpm, and deb packages? is that feature what makes it need to reload after update? likewise, are all package managers able to do this from the download site as well as the repository?
Trust me: all packages are signed and Linux deb and rpm packages have shasums in the package itself.
The packages are updated daily on the OS you use, Linux does this in background, Windows shows a message if new updates are available. Reload after Update only occurs on Windows; why? because the Autoupdater needs restarting the browser.