E: Package 'steamcmd' has no installation candidate
Solution 1:
A quick scan (rmadison steamcmd
)
guiverc@d960-ubu2:/home/wallpapers$ rmadison steamcmd
steamcmd | 0~20130205-1 | xenial/multiverse | source, i386
steamcmd | 0~20130205-1 | bionic/multiverse | source, i386
steamcmd | 0~20180105-3 | focal/multiverse | source, i386
steamcmd | 0~20180105-4 | groovy/multiverse | source, i386
steamcmd | 0~20180105-4 | hirsute/multiverse | source, i386
(or via web browser; https://packages.ubuntu.com/search?suite=all§ion=all&arch=any&keywords=steamcmd&searchon=names)
shows the command is only available for i386 architecture; ie. not a raspberry pi using armv7 or arm64. Your pi has the wrong CPU for steamcmd