Custom Categories will get you fairly close to what you want with minimal effort and maximum sustainability: Create or modify custom categories | ServiceNow Docs
Note that by default the categories are expanded unfortunately (can't be changed - yet at least), so if you only have two categories, the user can easily click the first HRSD category to minimize it, then easily see all the ITSM topics. Not ideal, but again, it's super simple and fully supported ootb. (p.s. don't forgot to go back to all your topics and add them to these new categories!)
The other option which I'm not recommending - because it's not very sustainable and is just generally not a good design - though totally doable ootb, is to just have two outward facing topics, then within those topics, do topic switches to the corresponding "sub"-topics, which are hidden to end users.
You control the visibility of topics using the Condition in VA Designer and/or the Is Topic Visible and Is Topic Discoverable fields on the sys_cs_topic table and you do a topic switch in a script with the following method:
vaSystem.switchTopicById() |
Enables the user to jump from the current conversation topic to the specified topic ID. The X button is available, so that the user can end the conversation. After the topic ends, the user resumes the global topic. When the conversation ends, the user can click to restart. |
Again, with rare exception this is a bad design because it prevents the user from interacting with the chatbot like the virtual agent it is supposed to be and it forces the user through additional potentially unnecessary steps (instead of just typing in what they want and using NLU - or even keywords). And of course any time you add or remove a topic, you'd have to update the "parent topic", hence unsustainable.
