Converting ARM Template to Terraform
I'm not aware of any tools available to convert ARM template to TF. I have used "azurerm_template_deployment" and I'm happy about it. My case was limited though.
Refer this github issue for more details,https://github.com/terraform-providers/terraform-provider-azurerm/issues/1115
It cannot be converted directly, but terraform can deploy arm templates using the azurerm_template_deployment resource. When setting the deployment type to 'complete', TF should also destroy the resource!
See the following link for an example that destroying also works: https://samcogan.com/deploying-arm-templates-with-terraform/.
You may want to check https://www.hcl2json.com/ if you want to convert between JSON and HCL (language used in TF)