As per Stephen, it will be more involved to change the number of nodes. The local network configuration is hard-coded for 5 nodes, and a different number of nodes will require a different genesis. Up to you if you want to hard-code or generate the required network configuration. Some relevant details for the generate option:

• tmpnet currently populates network configuration (i.e. node keys/ids and genesis) as part of network start. For the xsvm test setup this is already performed because its necessary to start the network to initialize the db state:

https://github.com/ava-labs/avalanchego/blob/master/tests/antithesis/compose.go#L65

• For the avalanchego setup, it will be necessary to ensure that network.EnsureDefaultConfiguration is called and that network.Genesis is set (likely to network.DefaultGenesis) to ensure that configuration is populated before compose configuration is generated.

• It will also be necessary for both setups to ensure that the compose configuration for each node embeds the network genesis. For the local case the genesis is hard-coded in the avalanchego binary, but for a custom genesis it will need to be provided.

Edit: Maybe makes sense for compose.go to always init a bootstrap DB (i.e. remove check for subnet count)? That would ensure consistent initialization of a generated network.