Awesome to see more first party Linux support, especially in a tablet form factor.
It's slightly disappointing to see a Mediatek SOC though, they've always had worse support for custom ROMs and kernels. Probably due to the cost comparable of Qualcomm chips.
Ubuntu Touch suggests that this will use Halium most likely, which is good for features, but ... it's not mainline.
Although: Thanks to Chromebooks, there are now a few Mediatek SoCs with okay mainline support. But while the Helio G99 seems quite similar to the Kompanio 520 at first glance, they are quite different, sadly.