Your plan seems like a huge waste of money to me: if this is your first mountain bike, you don’t even know what you like and how the mountain bike would fit into your riding (you still have a gravel bike, too …). You don’t know what kind of trails or tours you will ride and what kind of geometry you prefer.
If I were you I’d spend one year on a bog standard middle-of-the-road mountain bike with decent components. Don’t get a bike with too much or very little travel (e. g. 160 mm or 100 mm) or one whose geometry is very “progressive”. With mountain bikes the variations between the different types are much, much bigger than, say, between endurance road bikes and aero road bikes. I would even suggest you go for a hard tail, but in case you opt for a fully, I’d definitely take one with an aluminum frame. If something happens, no big deal, because with mountain bikes, you will crash much more often. After one year you know whether you want something more sporty or less sporty, with more suspension travel or less.
Then you can spend big if you’d like and if you can, but then you will also know better what your dream bike actually is. For me it would be an XC machine, but for others it would be a trail muncher.