Azure has an upcoming capability to export resource templates from the Azure Portal in Bicep format. This capability is actually already added to a new version of the Export Template REST API operation. You can test this by setting the appropriate outputFormat parameter which takes a value of either Json or Bicep from the Azure.Deployments.Core.Entities.ExportTemplateOutputFormat enumeration. Below is a PowerShell script to export a resource group as a Bicep template without local ARM decompilation.
$resourcegroup = 'MyResourceGroupName'
$groupid = az group show --name $resourcegroup --query id -o tsv
$token = az account get-access-token --query accessToken -o tsv|convertto-securestring -force -asplaintext
irm -method post -authentication bearer -token $token -uri "https://management.azure.com${groupid}/exportTemplate?api-version=2024-06-01-preview" -contenttype 'application/json' -body (@{resources=@('*');outputFormat='Bicep'}|convertto-json -c) -responseheadersvariable bicep_headers
do{start-sleep -s 1;$bicep = irm -method get -authentication bearer -token $token -uri $bicep_headers.location[0] -statuscodevariable bicep_status;write-progress -activity "Waiting for HTTP 200" -status "$(get-date -f 'o') got HTTP $bicep_status"}until($bicep_status -eq 200);
$bicep|select -exp output