Opening a non-public channel without initial routing sync seems to be an optimal option for a bandwidth and computation constrained Lightning node primairly focused on payments rather than payment routing (a lightweight mobile wallet for example). Let's suppose such a minimal node A is connected to a public node B via a non-public channel, this implies that node A needs to add a B -> A routing tag to it's payment requests which means it needs to have an access to B's latest fee and cltv_expiry_delta.

Currently localfeatures allows for all or nothing initial routing sync options but what if a feature bit could be added which would instruct a node B to only send an info sufficient for A to add a routing tag to it's payment requests and nothing else?