Sir. You seem to be making this far harder for yourself than it is.....and possibly far more expensive.
Firstly, as has been said above, pretty much any old frame with a 135mm and 68mm bb shell will do what you want.
Secondly, why spend loads on modern stuff for it when a simple 8 /9 speed cassette and triple front will give you all the gearing your ever going to need.....unless your cycling up walls for fun.!
If you really want 1x then why not get a chainset and just put one ring on and the biggest rear 9 speed you can cheaply find.
I used this for several years....think it cost £300 tops second hand parts! It flew up hills and cruised pretty well too.
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