How to import default content after/alongside migration?

Problem/Motivation

We are building a website where we:

• Use migrate to import content from the old D7 site. The migration keeps all the auto-increment ids (node ids etc) from D7.
• Use default_content to create landing pages, which are not part of the migration.

By default, all modules are installed _before_ the migration, based on config/sync/core.extension.yml.
This would mean that the landing pages are created before the migration.

However:

• Landing pages might depend on migrated content.
• Landing pages must be created with ids that don't clash with the ids from the migration.

Steps to reproduce

Proposed resolution

I can think of two directions how to solve this:

Either we find a way to import the default content _after_ the migration is complete.
Here we get into the territory of ✨ Allow manual imports Postponed

Or we avoid dependencies on migrated content, and crank up the auto-increment counter in the db tables before any default content is created.

I am posting this as an open-ended question, I am curious what solutions people use.

Remaining tasks

User interface changes

API changes

Data model changes