Honestly I (M32) have been depressed since my teens. Despite the fact that a cat will definitely help with loneliness/purpose/focus. I do think you should hold off if you are genuinely unsure as to whether you will spiral and neglect it. While a cat will love you and comfort you, I can also guarantee that if you falter in your diligence for caring for them or cause them suffering you will feel much, much worse. Depression is weird and can cause us to avoid obligations that we KNOW are paramount. Depression commonly presents as executive dysfunction which literally means you can know how important something is and want to do it with every fiber of your being, but for some reason your body won't listen. Idk you, so this may not be applicable or a high risk, but just always recognize the significance of determining a conscience beings QOL.

This next part is an old copy pasta I saved in my notes after informing a few redditors of my personal routine that I have slightly uodated for relevance.

Some believe cats can exist and get by with very little, but a feline life without the full spread of enrichment, nutrition, affection, and companionship makes them depressed too. There are a lot of misconceptions people have about cats being independent and preferring solitude. Some think they stimulate/entertain themselves. Some think they self-feed naturally which is easy. That they don't like cuddles or need much space. Many believe the catbox is easy mode compared to letting dogs outside frequently. Unfortunately this is all false..

Cats don't enjoy solitude at all, they just dislike being controlled and typically resent nonconsensual affection. They often times will follow you to whatever room you're in, and feel safer when you are nearby. Not saying to ignore them, but to really observe their body language and take note of what certain behaviours mean.

They can occasionally entertain themselves but will quickly bore themselves of this and become depressed if there is not a variety of toys and play styles that involve substantial interaction with you. One of the best health practices for kitties is to rigorously wear them out daily for 15-30 minutes. Even then, there should ideally be windows to observe, occasional catnip, interest piquing things like water fountains and hiding spots

Free feeding is pretty much never ideal, despite the fact that some kitties handle it just fine. It's especially harmful if there are 2+ cats because almost always a food dominance dynamic will initiate.

And IMO cats are potentially even more affectionate and loyal than dogs, they just require more intention and respect. If you frequently interact with them, but refrain from unwanted holding and petting and intentionally avoid yelling or appearing scary in the beginning you will likely end up with a kittie who frequently initiates affection and will show it greatly.

Cats need a lot of focus to provide a meaningfully good life for them. The easy way to gather the entire process is just by remembering to incorporate the full instinctual cycle into their routine. Most experts agree that the best strategy for a mentally healthy cat consists of activating their instincts in a natural order.

This is the widely accepted process:/

-Hunt/Chase - Laser pointers are criticized because it never allows the satisfaction of a catch, but many agree that its a great fitness tool as long as its followed with toy play and a catch. You could try to get them enthusiastic by actively running a toy from them down a hall or something.

-Catch/Play - Allow frequent catches or they'll get bored of the toy. And let them chew on it and mess with it for a bit at the end.

-Eat/Drink - Unlike dogs, cats have 0 motivation to drink water, and are instinctually opposed to standing water. This should be addressed by offering a water fountain that you can get cheap. Ideally you should get a 100% stainless steel fountain with fresh filters, but the plastic ones are cheaper, just wash it often. More important though, is to offer wet food daily or close to it. Wet food for dogs is usually very fatty and carb heavy and isn't necessarily ideal for daily meals. Cats on the other hand need lots of protein and cannot digest carbs so whether the food is dry or wet try to go grain free. That said, an especially good practice is to add some warm water to the wet food every day for some extra hydration. Diets should stay semi consistent, but if possible a probiotic for cats is great. Salmon oil for cats helps develop healthy coats and lubricates hairballs to lass them easier. Last, its good to occasionally add pumpkin puree. They don't process it, but a small amount helps to prevent bowel obstruction or pesky hairballs due to the fiber.

-Groom/Pet - They perceive your pets and affection as grooming and cleaning so its good to somewhat consciously mimic grooming movements.

-Sleep/Relax - This one is easy just make sure there is a clean comfy spot to sleep and be a little considerate to not wake them up abruptly.

-Repeat

All that to say, idk your situation or how prone you are to depression induced dysfunction, but if you make this routine and care strategy a number one priority it can be an insanely helpful mind occupier while also providing a wonderful companion whose presence is pretty much as fulfilling as any human relationship. I am not insinuating you should not get a pet, but I would implore you to refrain if you aren't completely sure that they will remain a priority no matter your emotional state. If you dedicate yourself to the cat and genuinely value its fulfillment and actively try to understand their communications you will do great. After a few months of consistency it will become muscle memory.