FeedReader is a free open source RSS desktop client for linux system. It supports web based RSS services like Feedbin, feedly, FreshRSS, InoReader, Local RSS, OwnCloud, The Old Reader and Tiny Tiny RSS. Using this you can synchronise you feed across all your devices. For ubuntu, it is available as Flatpak package. To install FeedReader RSS desktop client on your ubuntu you need to install flatpak first. please go to the below link to install flatpak on ubuntu.
How to install How to install flatpak on ubuntu
Install FeedReader RSS desktop client on Ubuntu
After the installation of flatpak on ubuntu, open the terminal app in ubuntu. Then run the below command in terminal.
sudo apt install xdg-desktop-portal xdg-desktop-portal-gtk flatpak
Type your ubuntu password if needed and confirm the installation by typing y.
Then run the below command to install FeedReader RSS client on ubuntu.
flatpak install flathub org.gnome.FeedReader
During the installation, you will be prompted to add the GNOME remote, just type y and hit the enter key. Then again to confirm the installation type y and hit enter key.