Compatibility with related packages

[sbfnk]

See epiforecasts/EpiNow2#555

[jamesmbaazam]

Potentially two pathways here:

• Be opinionated here and let adopters align with it. This is inevitable in some aspects of implementation but can be flexible in others
• Develop to align with the related packages. This option is the least disruptive but potentially more difficult and could lead to scope creeps.

[seabbs]

I think as this is an interface we don't need to align elsewhere but make sure we are providing useful outputs that meet the use case (which we should define).

In terms of the contents of that issue yes I agree where possible we should use useful low level functionality others have written but I feel we would always do that so not clear it needs discussion