For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/CrossToolchain:avr/openSUSE_Tumbleweed/CrossToolchain:avr.repo
zypper refresh
zypper install Arduino
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/CrossToolchain:avr/15.5/CrossToolchain:avr.repo
zypper refresh
zypper install Arduino
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/CrossToolchain:avr/15.4/CrossToolchain:avr.repo
zypper refresh
zypper install Arduino