Yes, it is possible to export all the power automate flows at once. I used the below PowerShell script to do that. Make sure you use the command "m365 login" in PowerShell before you run this script. I hope it helps.
#Step 1 - Get the default environment
Write-Host "Querying for default Flow environment..."
$environment = m365 flow environment list --output json | ConvertFrom-JSON
Write-Host "Found $($environment.Count) environments"
Write-Host "flowEnvironments: $($environment | Out-String)"
#Make sure which environment you want to export flows form "$environment[1]"
$defaultEnvironment = $environment[1].name
Write-Host "Found default environment $defaultEnvironment, querying Flows..."
# Step 2 - Get the flows info
Write-Host "Getting flows info..."
$flows = m365 flow list --environment $defaultEnvironment --asAdmin --output json | ConvertFrom-JSON
Write-Host "Found $($flows.Count) Flows to export..."
# Step 3 - Export the flows
$flows | ForEach-Object {
Write-Host "Exporting as ZIP & JSON... $($_.displayName)"
$filename = $_.displayName.Replace(" ","")
$timestamp = Get-Date -Format "yyyymmddhhmmss"
$exportPath = "$($filename)_$($timestamp)"
$flowId = $_.Name
m365 flow export --id $flowId --environment $defaultEnvironment --packageDisplayName $_.displayName --path "$exportPath.zip"
m365 flow export --id $flowId --environment $defaultEnvironment --format json --path "$exportPath.json"
}
Write-Host "Complete"