BPQ32
LinBPQ / BPQ32 is node software which is current and maintained.
* here is a guide on getting it running on the Raspberry Pi.
* here is a guide for Ubuntu/Linux Mint/Debian computers - like an old laptop.
LinBPQ is a highly configurable and flexible piece of software - this makes it fairly complex. It seems fairly likely a good number of people on the national network will settle on using LinBPQ, however there will be standards and simplification to help matters - maybe even scripts / a downloadable image. If you play with LinBPQ now, and you wish to join a national network project, expect to need to change your configuration to match.
[An example config file is here for reference if needed]
A BPQ32 node offers standard applications for Chat and mailbox (BBS) and can be extended to support custom applications. Here is a guide for adding a custom application to a Linbpq node.