GDevelop now supports tilemap painting with collisions. Read the release notes here: Release 5.4.207 · 4ian/GDevelop · GitHub
When will GDevelop an engine tilemap painter, because using 3rd party software can be iffy and dosen’t work most of the time.
While there are plans to integrate LDtk the same way yarn or piskel are integrated, there is no plan of adding a special tilemap editor to the scene editor. External editors like LDtk are literally made for the job by talented professionals, it’d be unlikely for the GDevelop the team to come up with a better solution.