The critical parts that are missing from all of those clients:
- Automatically performing HTTP/DNS challenges against your Plesk service (uploading challenge files to your webroot, setting challenge DNS records)
- Calling the Plesk API to install the certificate
Yes, there are many ACME clients that you could use, however the crucial part is the above. I don’t know of anything other than the official Plesk Let’s Encrypt plugin that integrates with Plesk like that.
If you have some programming/scripting chops then you could extend those clients to do that, but I doubt any of them can do it out of the box.