Did you try our official AppImage version of Sigil for many x86_64 based Linux distributions? It is available on our Releases page for the last couple of Sigil releases.
https://github.com/Sigil-Ebook/Sigil/releases
It is how we now support Sigil on Linux directly.
If your distribution is too old for even that to work, your only option is to build it from source as long at you can get a version of Qt >= Qt 6.4 installed on your system.