I've been quoted two vastly different estimates (in days) for an upgrade from Magento 2.2.8 to Magento 2.3.x (latest).
There are some custom modules and integrations to CRM.
Now, I realise without seeing the site and config, etc. there are a lot of unknowns but please can you let me know what I should be expecting here (a range would be great)?
If there is any more information I can give to get more accurate estimates,
please let me know. Note, I can't give site identification details, etc.