Here member nonsuch has made the best guide to resurrect N900 with the old Maemo Fremantle system:

https://dt.iki.fi/nokia-n900-resurrect

Follow these instructions if you need to get N900 to work atleast somehow right now.

If you are not in hurry wait and I believe in the end of year 2022 new Maemo Leste system may be ready for daily use.

https://maemo-leste.github.io/

I believe N900 may not be enough for your needs.

There is F(x)tec Pro1 X:

https://www.fxtec.com/pro1x

But if you are used to Apple level support this is not for you 'cause it seems it may be difficult to get any support easily.


The is also Astro Glide 5G which is coming out this year:

https://store.planetcom.co.uk/produc...41399314055362

And there is Pinephone which you can get keyboard case:

https://pine64.com/product-category/...e-accessories/

And there are of course many pages of other keyboard phones which may not be suitable for you with their low specs and old tech:

https://www.wirefly.com/guides/best-...werty-keyboard