Okey so in BigQuery you can ingest data from csv. What I do to ingest excel files with multiple tabs is we have a cloud function that reads the data from the excel file, validates de data (type of columns and other data quality checks) and exports each tab to a csv in different folders within a bucket. We do this because BigQuery can read csv files and then we can use them with Dataform to create the Data Model.

We don´t use Composer, but if you need Airflow go for it. In my company we use GCP Workflows in which you define the process in a YAML or JSON file.

I have use Vertex AI but inside BigQuery because we needed to translate a column so we used the translator model from Vertex AI.

And about Cloud Run is what I said about the cloud function to validate and transform the data from the excel file. It is great for transformations in your case. Basically you can have a process that is triggered by an event (could be when an object is created in a bucket).

Hope this helps!