I was able to use message card itself for inserting HTML in the way below, the HTML went as a value against the key "text" and I made it a separate group under sections
{
"@type": "MessageCard",
"@context": "http://schema.org/extensions",
"themeColor": "0076D7",
"summary": "XXXX",
"sections": [
{
"activityTitle": "XXXX",
"activitySubtitle": "",
"activityImage": "",
"facts": [
{
"name": "XX",
"value": "**1**"
},
{
"name": "YY",
"value": "**test**"
}
],
"markdown": true
},
{
"startGroup": true,
"text": "Task | Status | Start Time | End Time |
---|
xxx | yyy | 14:25 |
xxx | yyy | 15:25 | 16:25 |
"
}
]
}