This one has a 435mm chainstay. May be an option.

https://m.aliexpress.com/s/item/32793037954.html?spm=a2g0n.search-cache.0.0.2ae3983eJMzleK#autostay

I have been also looking at the BXT bikes. What made you choose this model? I'm currently looking at the BXT-MTB-009 it has a shorter chain stay and should make it a little more nimble. But it does use a smaller diameter seat post. Also interested if anyone has used this brand before so will be following your post.

https://m.aliexpress.com/s/item/32793037954.html?spm=a2g0n.search-cache.0.0.319b424dVviTns#autostay