I would like to point out that the support for string types in DSDL is currently marked for inclusion in the v1.0 release. The technical proposal is outlined here:
The implementation can be carried out easily without affecting the existing deployments. The lack of native string support is known to affect certain applications dealing with registers and file transfers (such as bootloaders). Here is one example: yakut reg produces wrong format on output for natural8 with option -d · Issue #65 · OpenCyphal/yakut · GitHub
The full list of issues scheduled for v1.0 is available here: Issues · OpenCyphal/specification · GitHub