Yeah, give borg a look. It's just faster to back up, faster to delete old backups, and just easier to do restores because so long as you have the appropriate credentials you can list the archive from any machine.
I think there's still a place/use for --link-dst and hardlinks, but as a backup system I think borg does it better.
Absolutely. Like most things on the Internet, it will get enshittified. I think it is very likely that at some point there will be "ads" in the form of the chat bot giving recommendations that favor certain products and services.
ERPNext is fairly easy to automate. We have a number of Python scripts that use the ERPNext API to create sales invoices, add and reconcile transactions from PayPal, Stripe, etc.
We originally used Quickbooks Online and I'm glad we decided to switch to ERPNext a few years ago.