You can't create views across database using the syntax you're thinking of.
Instead you could create a view on each database and use that in your view:
create view view1 as
use
select * from db1.schema1.view1
union all
select * from db2.schema1.view1
union all
select * from db3.schema1.view1
union all
select * from db4.schema1.view1
Make sure you vae permissions to select from those views and matching columns.