Hey @Jesse Suna ,
There are currently two deployment options for ESLZ:
The 1st party Enterprise-Scale Landing Zones reference implementation with the portal experience based on ARM templates
and the 3rd party Enterprise-Scale Landing Zones Terraform module, that has parity with 1st party implementation, where you can deploy, manage, and operationalize the Azure platform.
As of writing this a Biceps deployment module is not available and currently not on the roadmap for ESLZ .
In general there is nothing that would stop you compiling your own Biceps definition, However keep in mind that the current ARM templates for the Enterprise-Scale Landing Zones reference implementations are developed for - and optimized for a curated self-service deployment experience in the Azure portal.
MS does not recommend nor support customization of these templates, as they are complex given the options provided, which lead to a lot of logical operators and conditions in the expressions we are using. Further, as they are optimized for portal deployment and to setup the entire Azure tenant with platform and landing zones, there's a lot of sequencing that are happening across the various ARM scopes (management groups, subscriptions, and resource groups).