I would suggest below steps to deploy your changes on production server.
Enabled the maintenance mode.
Run below commands:
PHP bin/magento setup:upgrade
PHP bin/magento setup:di:compile
PHP bin/magento setup:static-content:deploy -f
If require provide correct permission for var, generated and pub folders.
If you get any error in any of the commands, you ...
When I created accounts, they were already confirmed, but they were disabled! This fixed it:
$customer = $this->customer->load($customerId);
Inside a custom theme would be the best approach to override this template.
LE: In a custom module there are several ways you could try this, check here the instructions from devdocs for Setting the template used by a block.
You need to be in developer mode but you can style your maintenance pages by simply adding
maintanence.html in your root directory and style it like any custom html page
You have to be in production mode though it wont work in devleoper mode
See the docs here