I build browser automation systems with either Playwright or Chrome Extensions. The biggest issue with automating 3rd party websites is knowing when the 3rd party developer pushes changes which break the automation. The way I dealt with that is run a headless browser in the cloud which checks the behavior of the automated site periodically sending emails and sms messages when it breaks.
If you don't already have this feature for your system, I would recommend it.
If you don't already have this feature for your system, I would recommend it.