Unfortunately no, .deb files are Debian packages. You need .rpm files (redhat package manager) BUT be careful, you have to find RPMs for Redhat 8.
freshrpms.net will give you these (look in the Psyche section). Also, look into getting apt4rpm, that'll let you install software by typing
apt-get install galeon
for instance, like on Debian (not everything can be installed that way though, known issue, me and some friends are working on a next gen packaging system).
If there is no rpm for Psyche, you'll need to compile from source, which is never fun. If you need to do this and can't figure out how, post here again and we'll explain it.