I've been working on a list of alt forms for total Pokémon Home completion and trying to determine which forms are still unable to be sent to Home. (Gen 9 are obviously just educated guesses as of now.) As far as I can tell, this is the master list:

-Able to be placed in Home
>All gender differences
>All regional forms
>Cap Pikachu
>Unown
>Deoxys
>Burmy/Wormadam
>Shellos/Gastrodon
>Rotom
>Shaymin
>Basculin
>Deerling/Sawsbuck
>Genies
>Keldeo
>Vivillon
>Flabébé/Floette/Floeges
>Furfrou
>Pumpkaboo/Gourgeist
>10% Zygarde
>Hoopa
>Oricorio
>Lycanroc
>Minior
>Magearna
>Toxtricity
>Sinistea/Polteageist
>Alcremie
>Urshifu
>Zarude
>Dudunsparce
>Maushold
>Tatsugiri
>Squakabilly
>Gimmighoul

As for the ones that can't be placed in Home, I have them categorized by reason:

-Battle only forms
>Megas/Primal Reversion
>Gigantamax
>Castform
>Cherrim
>Darmanitan
>Meloetta
>Greninja
>Aegislash
>Xerneas
>100% Zygarde
>Wishiwashi
>Mimikyu
>Ultra Necrozma
>Cramorant
>Eiscue
>Morpeko
>Palafin

-Held item required
>Dialga/Palkia/Giratina
>Arceus
>Genesect
>Silvally
>Zacian/Zamazenta

-Fusions
>Kyurem
>Dusk Mane/Dawn Wings Necrozma
>Calyrex

-Forever trapped in past games
>Spiky-ear Pichu
>Cosplay Pikachu

-Never Evers
>Eternal Flower Floette
>Eternamax Eternatus
>Starmobile Revavroom

Does this all look correct, or have a missed or wrongly placed anything?