The Israeli accessory website Zahal.org sells an aluminum handguard rail for the TAR-21.Not long after the release of the new bullpup, Lt Werner has demonstrated that it installs on the Canadain version and most likely on the new USA civilian Tavor SAR. While I have not performed this modification to my own rifle, I do feel it would assist in handling with my isosceles style of rifle shooting.
Unfortunately Zahal doesn’t currently have any other useful Tavor accessories. However, it is only a matter of being patient to see new products come available from TBD sources.