True, you are right, it works now perfectly fine! Ty for your advice. May there is something to add to the commands so that won't happen for others in the future. Appreciate your work!

For anyone who got the same issue...

• sudo flatpak remote-delete signal-arm
• flatpak remote-add --user --if-not-exists signal-arm https://elagost.com/flatpak/signal.flatpakrepo
• flatpak install signal-arm org.signal.Signal

Issue on installation can't find Platform but installed

see ~$ sudo flatpak install signal-arm org.signal.Signal Looking for matches… error: The application org.signal.Signal/aarch64/master requires the runtime org.freedesktop.Platform/aarch64/22.08 which was not found

~$ flatpak list Name Application ID Version Branch Installation Betterbird eu.betterbird.Betterbird 102.4.2-bb23 stable user Freedesktop Plat… org.freedesktop.Platform 22.08.3 22.08 user Mesa ….freedesktop.Platform.GL.default 21.3.9 21.08 user Mesa ….freedesktop.Platform.GL.default 22.1.7 22.08 user openh264 org.freedesktop.Platform.openh264 2.1.0 2.2.0 user Freedesktop SDK org.freedesktop.Sdk 22.08.3 22.08 user CrosAdapta org.gtk.Gtk3theme.CrosAdapta 3.22 user

uname -a -> Linux penguin 5.10.147-20144-g886d3d1da6b3 #1 SMP PREEMPT Wed Oct 26 22:51:36 PDT 2022 aarch64 GNU/Linux

~$ flatpak remotes --columns=name,url Name URL signal-arm https://elagost.com/flatpak/repo/ flathub https://dl.flathub.org/repo/