This video explains how to create SharePoint Search in Power Apps using MS graph API directly without using any flow or powerapps.
This video also explains how to parse the response of MS graph API to bind to gallery.

Formlae for Gallery
------------------------
Set(requestbody,"{
""requests"": [
{
""entityTypes"": [
""listItem""
],
""query"": {
""queryString"": """&TextInput1.Text&"""
},
""fields"": [
""id"",
""name"",
""title"",
""webUrl""
]
}
]
}");

Formulae On select
-------------------------------
Please look at pinned comments for varFile full base 64 file (as its too long)