hmm
I wouldn't recommend buying a coop even if you can afford it
most pre fab coops are made out of cheap, thin wood and are not predator proof. I learnt that the hard way

all the fox had to do was open the door
also few months ago had the doors and roof of mine fly off in 30mph winds.
it would be much better to make your own, cheaper and much safer for you chicken.
id also recommend (like everyone else) buying it a buddy if you're too attached to it. however I also would urge you to look into giving it another home if your dads not getting convinced enough to get another one even if you have become too attached. it would be much more natural and better for the chicken, it needs to hang out with chickens, not humans.
try begging your dad even more
in the meantime, stick a mirror on the sides of your brooder
add beanies
add a
stuffed chicken toy which it probably wont be fooled by but its better than nothing
get
a giant chicken that has a nest which it also might not be fooled by but it can crawl under it and on the nest for safety or comfort
I don't know if these are the best things though ^
play some comforting mama hen clucking noises for it so it is calm
again I DONT know if this will work, just saying what I might try if I was in your position
add a feather duster to hang from the ceiling of your brooder which will feel like a mama hen
make sure if its ostrich feathers or something to cut loops of the feather so it doesn't hang and get strangled by it or trapped in it
BEST OF LUCK AND I HOPE YOUR DAD ALLOWS YOU TO GET SOME BROTHERS/SISTERS FOR YOUR BABY
