The titles will be called Pokemon Apex Diamond and Zenith Pearl.

The story is more or less the same but with Dynamax/Gigantimax phenomenon integrated. Eternatus was found to be in a chamber underground of Sinnoh which creates dynamax spots all over the region. You can battle it by mining underground in post game.

Dialga and Palkia get upgraded Roar of Time and Spatial Rend moves when they hold Adamant Orb and Lustrous Orb fused with Dynamax material. They get corrupted and unlock their Eternamax forms when they use these moves.

Dialga looks like a huge pillar of diamond with arms and legs, surrounded by more diamond crystals and blue gas. Palkia looks like its encased in a pearl in a huge alien clam with space distorting around it covered in white gas.

You get to visit Cyrus' new world before you catch the box legendary.

No full customization but there will be clothing options similar to Lets Go Pikachu and Eevee.

Starters, Vespiquen, Cherrim, Gastrodon, Lucario, Rampardos, Bastiodon, Pachirisu, Garchomp, Abomasnow, Drifblim, Honchkrow, Hippowdon, Bronzong, Cresselia, Darkrai get gigantimax forms.

Arceus gets Alphamax form. Looks like a divine angel with many wings and gold rings. Very godly looking.

No battle frontier instead they have a similar tournament to Galarian star tournament.

Some areas like Great Marsh, some routes, Mt Coronet, the trio lakes turned into wild areas. There is also a new wild area in the map. Very expansive.

No Giratina or distortion world arc. Maybe DLC?

Maybe part 2?