How about being able to modulate The data byte within a sysex string.
Check out Extra Transform options (NRPN/SysEx)? for some background and discussion on the topic.
Yes, we’re tracking the topic linked by @pmatilai, please add any further details you’d have in mind for this feature.
Let’s say a string of 16 sysex Bytes each byte being mappable, probably except first byte being fixed to F0 the rest being 1-127, data, F7. The strings length can then be flexible, including checksum would probably be difficult. The byte designated as data could then be modulated by eg Lfo.