My understanding of what you’ve described is that those above you don’t think you’re ready for the role yet.
As a result, you have two options, here.
Option 1 is apply for the job and use the interview to prove that you are ready for the next role. Whether they hire you for it or not is up to them, but it shows willing and enthusiasm for your own career progression.
Option 2 is you wait, complete your training over the 6 month period and then have a discussion about the role that is going to be “created” for you.
However, some advice-
I was in your situation a year ago. I was promised I’d get x, y and z training and be put forward for promotion as soon as possible. 4 months went by and I received absolutely 0 training (there was always an excuse; “too busy” on these days to do anything, can’t do it this week because x has left, etc, etc). My current role at the time was boring the tits off me by this point and I was no longer happy in work. I knew I had to do something off my own bat, as my manager certainly wasn’t going to fulfil what they had promised.
A role came up that was perfect for me and exactly what I was looking for. I applied. Out of decency, I did tell them before I applied. The conversation that followed was the most reaffirming conversation I’ve ever had in my numerous years for the company that you should always put yourself first. So many excuses for why I wouldn’t get the role (all centred around the training that they had failed to provide me). It was very clear at that point that they actually had no intention of training me, and wanted to keep me at the level I was at because it was easier for them.
I got the job (they hadn’t ever seen my CV as they were a replacement manager for the manager who had hired me, I had suitable experience that filled the gaps from another role I was previously in). I have done very well in the role and haven’t looked back. However, if I didn’t get the role, I was fully ready to leave and work for another company. I had already began my job search in case that role didn’t work out.
So, ultimately, I think you should apply for the role. Your manager might have honest intentions with their plans for you, but that doesn’t mean everyone else will.
Always put yourself first and don’t rely on promises until you see something in writing that confirms the position is going to be offered to you. In nearly every single job I’ve ever had, I’ve seen so many people screwed over by false promises/promises that were never delivered (for whatever reason). The thing that everyone had in common in all these circumstances was that they “trusted” their manager would sort it for them. They never did, or they rescinded the offer because someone they liked more was available, and other reasons similar to this.
You have to take control of your own career, and not leave it to chance. Work on your application over the weekend and have it ready to send off next week. Do interview prep and try to fill as many training gaps as you can in the next week or two.
Maybe you won’t get the role, but it’s better to try and know you didn’t let the opportunity pass you by, than not do anything and regret it.