ffmpeg video0 to fb0 webcam to hdmi

Hi Folks!
having a bit of a time trying to get ffmpeg to read from the webcam and output it to the hdmi port. the real problem is I’m pretty new and I’m not really understanding the options past input and a few others… so I’ve tried

sudo ffmpeg -f v4l2 -i /dev/video0 -pix_fmt rgb565le -f fbdev /dev/fb0

which nothing happens, ive tried omitting options etc to no avail. I either get
“Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)”

or

Unable to find a suitable output format for ‘/dev/fb0’

so I’m not really sure which options I need, if anyone can help me with this that would be great!!