Bought the iPad recently and to be honest the operating system is a massive failure. Don’t wanna go into details but the general every day usage on Android is 10x better

Exactly, and that must be why every major business, corporation, hospitals, banks and restaurants that uses tablets (which is the majority) only use iPads. They are certainly not using Android tablets.

Why would ask a forum? It’s your decision.

I don’t know why benchmarks matter to anyone anymore. No matter what AMD nor Intel have current processors that are better than Apple’s SoC’s in overall performance and efficiency. Sure a PC fanboy can come here and scream SPEED, but he’ll also be screaming SHORT BATTERY, HEAT, LOUD FANS. At this point today’s computers are super fast for just about every demanding task. What’s most important are long battery life on full performance, bright screens with minimal effects on battery, no fan noise and low heat. Nothing by AMD or Intel can match that.

The 2015 Macbook is not “over 7 years old”, it’s almost 9 years old, and it’s a good chance that Apple either does not carry parts for such an old machine or they don’t want to deal with the liability of performing out-of-warranty service for such an old Mac, because if anything goes wrong they have to take responsibility for it. I’m just giving you my take.

Like others said your only option is to find a 3rd party local repair shop and have the install a 3rd party non-Apple battery if you want to keep using it.