I built several of these years ago for all the non-CEC capable TVs in the house. I never heard of FLIRC until recently, but these basically did the same thing. The arduino emulates a USB keyboard and sends appropriate keystrokes based on the IR signals it receives from the TV's remote.
in the pre-covid days I was buying bunches of these generic pro-micro arduinos for less than $4 each, and the VS1838 IR receivers for 5 for $5. sadly, the chip shortage has pushed up the prices of arduinos...