I just did a test with the following body and I could add an info panel as part of a comment to a Jira Cloud site.
Here is a screenshot for your reference:
"body": {
"content": [
{
"content": [
{
"text": "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Pellentesque eget venenatis elit. Duis eu justo eget augue iaculis fermentum. Sed semper quam laoreet nisi egestas at posuere augue semper.",
"type": "text"
}
],
"type": "paragraph"
},
{
"content": [
{
"type": "paragraph",
"content": [
{
"type": "text",
"text": "Hello world"
}
]
}
],
"type": "panel",
"attrs": {
"panelType": "info"
}
}
],
"type": "doc",
"version": 1
}
}
In the example above, I’ve added some text to show how to add multiple nodes to a single comment but it’s 100% possible for the comment to contain just the info panel: