Look:
I think you search that: https://developer.hashicorp.com/vault/tutorials/pki/pki-engine
Just my opinion: No need to focus on reddit. The world is not focused by that platform, and there are other people on the Internet.
To attract an audience, you need exactly to attract an audience. Add indexing by search engines, Add SEO optimization for lemmy-ui, etc. People can find interesting instances exactly in google search after that without any provisioning. That’s why web search engines be created.
It all depends on the writing time. if you have about a year, it will be difficult to make something truly breakthrough.
For example, we can question the modified Harvard architecture of modern processors. But creating an alternative architecture based on a modern set of hardware may be a bit of a difficult choice for a thesis.
The industry has not acquired a single standard by now. In this regard, there are many different devices on different protocols. Many manufacturers generally link their devices only to their own cloud.
Of the popular open standards, I would recommend zigbee. But in order for the device to be correctly identified, its sensors and parameters must be supported by the server. Zigbee2MQTT is a good choice. I use it myself. But the compatibility is not complete and you need to check the support on the developer’s website ( https://www.zigbee2mqtt.io/supported-devices/ ) or buy one device for the test.
I recommend Tuya company. I have about 12 switches from this company and they work pretty well with zigbee2mqtt.
The complete scheme is as follows: zigbee device <-> radio channel <-> zigbee coordimator <-> zigbee2mqtt <-> mqtt <-> homeassistant. For connect devices to zigbee2mqtt you need coordinator. SONOFF ZBDongle-E for example. Add zigbee routers if you have big square. If you server not in good place you can use wifi2zigbee coordinator. HamGeek poe zigbee 3.0 for example.
In general, this is of course 100% based on speculation, but I assume that you can connect to a VPN but you cannot access any resource inside the local network. Just because this is the most basic mistake that beginners usually make. And it’s related to the fact that your pi is not your default gateway. To solve this, you need to enable SNAT on the local Pi interface. There are many guides on the Internet on how to do this.
P.S. Unfortunately, I have a poor telepathy skill, so it would be good to get a little more background. At least an accurate description of the problem. =)