Directories:

VendorName/
VendorName/ModuleName
VendorName/ModuleName/Block
VendorName/ModuleName/Plugin
VendorName/ModuleName/view
VendorName/ModuleName/view/frontend
VendorName/ModuleName/view/frontend/layout
VendorName/ModuleName/view/frontend/templates
VendorName/ModuleName/view/frontend/templates/page
VendorName/ModuleName/view/frontend/templates/order
VendorName/ModuleName/etc

Files:

VendorName/ModuleName
composer.json
registration.php

VendorName/ModuleName/Block
Success.php

VendorName/ModuleName/etc
di.xml
module.xml

VendorName/ModuleName/Plugin
SuccessPlugin.php

VendorName/ModuleName/view/frontend/layout
checkout_onepage_success.xml
default.xml

VendorName/ModuleName/view/frontend/templates/order
success.phtml

VendorName/ModuleName/view/frontend/templates/page
header.phtml