Public/Set-FMTFlexVnetRole.ps1

function Set-FMTFlexVnetRole {
    param(
        [parameter(Mandatory)]
        [string] $flexRG,
        [parameter(Mandatory)]
        [string] $flexVM,
        [parameter(Mandatory)]
        [string] $vnet,
        [parameter(Mandatory)]
        [string] $vnetRG,
        [parameter(Mandatory)]
        [string] $role
    )

        $flexVMObj = Get-AzVM -Name $flexVM -ResourceGroupName $flexRG
        $flexrole = Get-AzRoleDefinition -Name $role  
        $flexVnet = Get-AzVirtualNetwork -Name $vnet -ResourceGroupName $vnetRG

        New-AzRoleAssignment -ObjectId $flexVMObj.Identity.PrincipalId -RoleDefinitionName $flexrole.name -scope $flexVnet.id
}