Hi and welcome!
I am very sorry for your loss! Kidney failure is very painful and incurable, so you have made the right decision, as heart-breaking as it is.
You are welcome to post a tribute to your piggy in our Rainbow Bridge section if or whenever it feels right for you.
No piggy is ever too old to be left on its own unless they decide so. The safest way of finding a new friend that is character compatible is by rescue dating your boar - provided that you can get to one of the recommended good standard rescues. You also have the rescue to fall back on in case there are problems along the way. When properly done, boar rescue dating can happen with boars of all ages, so you do not have the teenage hormone problem. The key to any boar bond is character compatibility and mutual liking, not age.
Here are our tips for looking after a bereaved piggy. They also contain links to recommended rescues. If you can tell us your country, state/province or UK county, we may be able to help with recommendations. We have got members from all over the world.
Looking After A Bereaved Guinea Pig
Alternatively, you and your parents can consider having your boy neutered, provided that you have got a good and experienced guinea pig or small furries operating vet in order to keep the risk of post-op complications down.
Then your remaining boy could live with a sow or two after a 6 weeks safety wait. if you want to get guaranteed healthy and not pregnant sows, please go to a good standard rescue with a mandatory pregnancy watch and quarantine as well as medical care while in rescue. Rescue dating is always the best way of finding out whether piggies accept each other for a happy long term bond. The link above also contains links to recommended vets in several countries if wished.
(On the latter point: the little baby in my avatar picture, Tegan, is the unplanned daughter of a supposedly safe over 5 weeks post-op boar, so it can really happen as late as that! It is not a one-off case)