As others have said they should be in pairs. P@H are shit though. They preach about animal welfare but most of their animals are kept in tiny, cramped cages, mixed sexed unneutered animals and as OP has shown, the staff are untrained.
Firstly, I'd check it was actually male. There are handy instructions online but possibly a vet, I'd get health checked asap anyway.
We have a C&C cage with fleece bedding towels first on the coroplast with a layer of fleece. This is spot cleaned twice a day for poop, and fully changed twice a week.
They should have an unlimited supply of hay (no straw, it's too hard as they can be susceptible to eye pokes) for dietary reasons, and unrestricted (so not in a hay ball or rack which are dangerous anyway). The more hay the better as it's great for sleeping, eating and playing in, it also is key in keeping their teeth ground down.
Get good quality, low calcium pellets (for adult pigs, younger pigs can have higher levels of calcium as they are growing) (no colourful ones). They should have a weighed amount of these a day and about a cup of veggies a day.
A good selection is key but they should be getting lots of vitamin C (bell peppers are great for this, ours will eat greens but don't like red or yellow too much). Leafy greens are a staple, but things like kale, spinach etc are high in calcium so limit to once or twice a week. Don't feed iceberg lettuce as can cause stomach issues. Gassy veg like broccoli, cabbage should be monitored as some are susceptible to bloat. Ours are ok, and eat loads of hay so are ok, but again once a twice a week. Fruit at a minimum for the sugar content, we give them maybe a grape a week lol (but we don't eat a lot of fruit anyway).
Boys will argue, but it's normal. You will need to introduce them sensibly. Lots of food and hay to keep distracted. Rumbling noises are just a sign of dominance, They can square up to each other and chatter teeth too. Chasing is normal, but watch out for them fighting properly. When blood is drawn they can't live together anymore.
We've had our two boys 3 years now and they rumble all the time, but then snuggle up together.