Postgres Composite types allow structured types to be used as column types:

CREATE TYPE phone AS (
    area text,
    numb integer
);

ALTER TABLE customers ADD phone_no phone;

Debezium should capturing values to such columns. Some open questions:

• Are changes to the logical decoding plug-ins needed?
• How to obtain information about the columns contained in a composite type?
• How to represent columns of composite types in emitted CDC messages? Could be done as an equivalent struct or just by adding the contained columns directly to the before/after structs. The latter increases compatibility with consumers, but it loses information about the containing composite type. This might be mitigated by adding the composite type name as a schema parameter of the schemas for the contained columns. That'd be my preference.