Tzeentch

Thankfully it is largely just a few commands with built in tools to tell the drive firmware to secure erase

SATA SSD: https://acceptdefaults.com/2023/01/06/secure-erase-an-ssd/

NVME SSD: https://acceptdefaults.com/2022/08/11/secure-erase-an-nvme-drive/

Veronica Explains comes to mind: https://www.youtube.com/channel/UCMiyV_Ib77XLpzHPQH_q0qQ

She is also on Peertube: https://tinkerbetter.tube/c/veronicaexplains/videos

This sort of exists https://reactos.org/

Key word on sort of, it’s quite rough in many areas

The themes section on the desktop integration doc here might be of use: https://docs.flatpak.org/en/latest/desktop-integration.html

This may be useful for further elaboration: https://www.reddit.com/r/flatpak/comments/y9jmqj/the_general_flatpak_qt_and_gtk_theming_guide/

Going off of these guides my best guess would be that you don’t yet have kvantum or some other theme runtime installed within flatpak

I’ll also mention Stylepack exists for automating and streamlining theme installation, it’s only for GTK currently however but maybe will be of use in future: https://github.com/refi64/stylepak