For local (GUI!) tools I find XCA (https://hohnstaedt.de/xca/) excellent. It has a few ready to fo templates out of the box, and you can make your own.
It's pretty good for having your own simple CA, self signed certificates or anything of the sort, as well as having a nicer interface for anything that's not one of the ACME providers (e.g. Let's Encrypt) or when you don't need CLI or automation.
I actually wrote about using it on my blog, which has plenty of screenshots: https://blog.kronis.dev/tutorials/lets-run-our-own-ca
It's pretty good for having your own simple CA, self signed certificates or anything of the sort, as well as having a nicer interface for anything that's not one of the ACME providers (e.g. Let's Encrypt) or when you don't need CLI or automation.