@mikail I don't have specific tips but want to offer a glimmer of hope and realistic expectations. We have an almost 3 year old purebred cattle dog that's been home with us since 8 weeks old and everyday I can see him getting closer to being a great dog. My partner grew up with dogs while this is my first. Oh...we also live in a large urban city because I apparently wanted to try dog ownership in hard mode.
As puppy, he seemed to have endless energy. Could fetch for literally 1-2 hours with only intermittent breaks...and I am talking about launching the ball hundreds of feet each time with one of those launch sticks. However, he was super cute, learned commands very fast and listened to them very well so it was easy to cope with the high energy even though I sacrificed most of my free time to exercise him. In terms of energy level, he did mellow out at 1 and again around 2 I noticed another huge drop where he will actually get tired from fetch quite faster and will want to stop playing. Currently, a 30 min session of fetch along with other tricks and indoor play throughout the day can keep him happy. When I work from home, he can now have stretches of 3-4 hours napping without bothering me. I can leave him out for 8 hours at home unattended and he is fine.
What I wasn't prepared for was the reactivity. I noticed signs of it around 8 months and it really kicked in around 1. I feel like we socialized him pretty well as a puppy but maybe the urban environment was too stimulating or we didn't handle his fear periods correctly, I'll never know. It was pretty terrible - barking/growling/lunging at dogs, people, cars, bikes, and just about anything else. Even redirecting onto us during those reactive moments. This time was one of the most stressful and emotionally difficult periods of my life; even more than the stress I felt when I did my bachelor and master engineering degrees together in under 4 years. It was a constant cycle of frustration, resentment, and guilt. I would be lying if I said that rehoming did not cross my mind. What ended up happening is that we spent countless hours and thousands on training. If possible I would encourage you to work with a trainer on the reactivity before it gets to the point that we reached. Now I can have mostly peaceful walks in the city and pass people and dogs with calm behavior over 95% of the time. He still struggles on some days but I noticed a pretty big reduction in reactivity around 2.5 years old and just recently again as he approaches 3.
If I had to do it all over again, I would tell myself that patience, structure, empathy, and consistency is key.