Concurrency / Transaction Concerns with PostgreSQL Copy (bulk insert)
Can I use COPY in normal transactions as I would other statements?


Yes, You can. This will invoke the trigger, check constraint and other
constraints as well. But it will not invoke the rules. It supports
MVCC and ACID.


Can mass COPY loads happen while the database is still live with normal production inserts and selects still running against other tables?


Yes, But its based on your workload. Do a test in Dev infra.


Can multiple connections concurrently perform COPY operations?


Yes it'll. But keep an eye on the resource utilization.


Am I crazy for thinking to treat this like any other PG command? Is it designed to be used against live, production databases or is it more of a housekeeping tool.


You can trust and use it in production. No issues.

References:

Read the Notes section from PG documentation

Someone implemented the same in Production with 10m rows file