file.ps1

$json = get-content "$PSScriptRoot/../init.json" -raw -Encoding ascii | convertfrom-json
$machinesTypes = $json.vagrant.'machines-types';

foreach($machineType in $machinesTypes) {

        frenchex2 vagrant:machine-type:add               `
        --name "${machineType.Name}"                    `
        --vcpus "${machineType.Vcpus}"                  `
        --cpucap "${machineType.CpuCap}"                `
        --os-type "${machineType.'os-type'}"            `
        --os-version "${machineType.'os-version'}"      `
        --ram-mb "${machineType."ram-mb"}"              `
        --vram-mb "${machineType."vram-mb"}"            `
        --no-3d                                          `
        --no-gui                                         `
        --provider "${machineType.Provider}"            `
        --enabled                                        `
        --box "${machineType.box}"
}

init.json

{
    "vagrant": {
        "machines-types": {
            "dev": {
                "vcpus": 4,
                "cpucap": 100,
                "os-type": "Debian_64",
                "os-version": "10.9.0",
                "ram-mb": 2048,
                "vram-mb": 8,
                "3d": false,
                "gui": false,
                "provider": "virtualbox",
                "enabled": true,
                "box": "debian/contrib-buster64"
            }
        },
        "provisioners": [

        ]
    }
}

param(
    [string] $Path
)

import-module "$PSScriptRoot/../posh_modules/Utils.psm1" -Force

if ([string]::IsNullOrEmpty($Path)) {
    $path = get-location
}

frenchex2 vagrant:init --instance "$Instance" --group "$group"

$json = get-content "$PSScriptRoot/../init.json" -raw -Encoding ascii | convertfrom-json

$machinesTypes = $json.vagrant.'machines-types'.psobject.Properties

foreach($machineType in $machinesTypes) {
    
        frenchex2 vagrant:machine-type:add               `
        --name $machineType.Name                    `
        --vcpus $machineType.Value.Vcpus                 `
        --cpucap $machineType.Value.cpucap               `
        --os-type $machineType.Value.'os-type'          `
        --os-version $machineType.Value.'os-version'        `
        --ram-mb $machineType.Value.'ram-mb'           `
        --vram-mb $machineType.Value.'vram-mb'          `
        --no-3d                                          `
        --no-gui                                         `
        --provider $machineType.Value.provider       `
        --enabled                                        `
        --box $machineType.Value.box
}

this is correct