E mountain bike in Australia for tall rider

[Andos2020]

Hi I'm 6 ft 6 and struggling to find a suitable e mountain bike for my height. It would seem that only cube offers a frame that would be big enough and they don't get delivered until after February next year.

I've looked at the trek powerfly bikes but worried the largest size might be too small. I've seen suggestions about getting a custom longer seatpost added to these models, is this a realistic thing to do?

Thanks for any advice