Does Cardano support multisig wallets? If not, are there any ongoing projects to have them implemented, any standards defined or at least drafts proposed?
CIP 1854 (Cardano Improvement Proposals) allows us to use Multi-signatures HD Wallets, but there's no implementation at the moment. However, in Goguen era, which begins on 12th September 2021, Cardano with the help of Alonzo gives developers the tools to create Smart Contracts with Multisig.
Here's a quotation from IOHK post:
Applying a rigorous approach based on formal methods and verification, Alonzo extends the basic multi-signature scripting language (multisig) used in Cardano Shelley. Multisig will be upgraded to the Plutus Core language for more powerful and secure scripting options.