Is a TV a settop box and a monitor? So, create composite video. You can display that on a VGA monitor with a converter.
I think the tuner would be the hardest part. The tuner of yesteryear was a big rotalry switch that switched in components an dit had a tunable slug for each station for fine tuning. Not frequency synthesis.
Only for VHF, which ceased in the UK last century, and was only ever used for the 405 (started pre-WWII) channels.