I sympathise OP, sorry this is long. I was in my late 30's when my knee arthritis was diagnosed (ex dancer and athlete) and no actual fall/trauma etc.
I was in agony and even lying absolutely still in bed was painful. I tried strapping on ice packs, hot water bottles, stuck on heat patches and tried any OTC med I could get. I did physio exercises and was at the point of saying I'd have a replacement because it was getting unbearable.
Do you know if your arthritis is worse on one side of your knee? Its often the inner side. There is a brace called a uniloader which was a gamechanger for me. I was seeing the orthopaedic surgeon and asking about treatment options and on hobbling out, I mentioned I'd bought a basic, tube brace from boots which did nothing. It was only then that he mentioned a uniloader brace. It uses straps and opens the side with the worse arthritis and puts your weight down the other side. Yes, this side will also wear, but getting relief from grinding was amazing.
Over the years I had 2 types. I'd recommend getting them on the NHS if possible so they can measure/fit you properly, plus, some are expensive. In saying that though, I'd have paid myself if I'd known the relief I'd get.
https://thuasne-store.co.uk/product/action-reliever/- It fitted under clothes so was discreet, but after a few months, the elastic loosened and didn't feel as supportive. I was given a 2nd one but the exact same happened. I did also lose weight due to being more active, but even so, I wasn't impressed at the cost and how quickly it lost shape.
https://www.mediuk.co.uk/products/m-4-s-oa-comfort/ This was not my exact brand, but to give you an idea of a metal type brace. It didn't fit under trousers and looked far more industrial. Some of the metal rubbed my skin, so I had to use little foam pieces to stop that.
I managed to wean myself off all braces after about 2yrs and weirdly, haven't had the same, debilitating pain since. If I do a longer walk or bend my knee too much, I do feel it the the next day. I still can't squat and do certain poses and will need a replacement in time, but so far, I can cope. I have no idea how/why though.
1 thing to note is that having a cortisone injection 'might' give some relief, but it can also delay surgery. I've heard of 2 people's replacements being delayed due to having the injection done. Wishing you all the best.