The Entitlement Analyzer app in cloud has the domains/users listed in the userSubject field. You could copy/paste the RestConnectorMasterTable in its own app script to get those values:

The code snippet:

RestConnectorMasterTable:
SQL SELECT
"__KEY_root",
(SELECT
"__KEY_links",
"__FK_links",
(SELECT
"href",
"__FK_self"
FROM "self" FK "__FK_self"),
(SELECT
"href" AS "href_u0",
"__FK_next"
FROM "next" FK "__FK_next")
FROM "links" PK "__KEY_links" FK "__FK_links"),
(SELECT
"id",
"tenantId",
"created",
"lastUpdated",
"status",
"name",
"subject",
"email",
"zoneinfo",
"locale",
"preferredLocale",
"__KEY_data",
"__FK_data",
(SELECT
"@Value",
"__FK_roles"
FROM "roles" FK "__FK_roles" ArrayValueAlias "@Value"),
(SELECT
"__KEY_links_u0",
"__FK_links_u0",
(SELECT
"href" AS "href_u1",
"__FK_self_u0"
FROM "self" FK "__FK_self_u0")
FROM "links" PK "__KEY_links_u0" FK "__FK_links_u0")
FROM "data" PK "__KEY_data" FK "__FK_data")
FROM JSON (wrap on) "root" PK "__KEY_root"
WITH CONNECTION (
URL "https://$(vu_tenant_fqdn)/api/v1/users?$(vParams)"
);

[Users]:
LOAD
trim([id]) AS userId,
[name],
[email],
Lower(subject) AS userSubject // have to do this as users and assigments API case varies on subject
RESIDENT RestConnectorMasterTable
WHERE NOT IsNull([__FK_data]);