MariaDB/mySQL is there a way to limit a user to SELECT and SHOW queries?
Use GRANT to give them the exact authority that you would like them to have. It sounds like they may only need SELECT. For global authority use:

GRANT SELECT ON *.* TO 'supportmember'@'localhost';

Or limit the authority to a specific database using:

GRANT SELECT ON specificdatabase.* TO 'supportmember'@'localhost';

Or to a specific table in a specific database:

GRANT SELECT ON specificdatabase.specifictable TO 'supportmember'@'localhost';