CW: Pet loss

My childhood cat recently passed away (in may). She was 13, almost 14 years old, and her death came quite sudden.

I have another cat, who's turning 3 this summer.

He's very active and playful, and since my first cat passed away, he has been acting a bit weird. Idk if I'm imagining things, but to me it looks like he's a little bored, and even more energetic, but has no one to play with. My first cat was never the super playful type, and as she got older she got even more laid back. She never really liked other cats, but was never mean to them or hurt anyone. The most she'd ever do is hiss. My newer cat however loved to mess with her and jump on her, so from his perspective they kinda played together. Now that there's no other cat to do that with I'm a bit scared he's bored.

Plus I know most cats do much better in pairs, or at least not alone.

I don't know if getting a new cat is a good idea so soon (as in this summer). I know it's more important for me to be ready for a new cat, but I don't have anything against it, only that this year would be too soon for me.

I still want to do the best for my cat too.

So basically my question is: Is my cat gonna be fine alone (maybe for years) or what should I do? My other cat was very much a loner type, but I think my new cat might do better in a pair, even tho he has beef with every one of my neighbors cats. My late cat didn't like company or cats, but she tolerated them, was never mean to anyone. My new cat loved to play with my other cat, but absolutely hates/is scared of every other cat. So I'm also scared, cuz what if I get a new kitty in the future, thinking my cat finally won't be alone, and he turns out to hate the new kitten, what then?

Sorry if this is a bit all over the place, I hope it still makes sense tho. Any and all advice is much much appreciated!!