What is the best way to save the data state of MySql/Redis/MongoDB/Clickhouse DBMS?

Question

MySQL

There is a project with millions of records in MySql and Redis / MongoDB / Clickhouse are also connected, which are also rather big, you need to take a snapshot of the system state without producing a significant load, as close as possible to a one-time one and without slowing down the site, then modify the data a little and transfer it as a dump to the customer. While I am considering such options for MySql/MongoDB:
1) Make a copy of the tables by adding a prefix to the name, process and save the dump under the same name. 2) Save a dump of tables (mysqlbackup), create tables from the dump with a prefix, process, save to a dump under the same name. CREATE TABLE NEW_TableName LIKE TableName

Answer 1

Maybe there is an opportunity to make a snapshot of the file system where the database lies?
Then it would be possible to deploy a snapshot somewhere, and there it would already be easy to prepare the data for transmission.