As someone who also has produced code that looks like random characters spewed onto a terminal while using fpdf, I feel this one.

It can still have issues with potential attacks that would redirect your client to a system outside of the VPN. It would prevent MitM but not complete replacement.

Likely you needed to include the intermediate cert chain. Let’s encrypt sets that up automatically so it’s quite a bit easier to get right.

The expression syntax for the GNU find command is very powerful. I would expect that it is up to the task. If you don’t have the GNU find command with it’s extensions I could see how it’s would be difficult.