As of SDP release 25.3, HBase 2.6.x is fully supported.
HBase 2.6 support was added with PHOENIX-7172 and released with Phoenix 5.2.1, which is included since SDP 25.3. SDP 24.7 included Phoenix built from the master branch from commit 4afe457.
Repository: hbase-operator-tools
This is now mirrored and built from source using patchable.
Care needs to be taken when back-porting upstream changes due to changing dependencies. A patch for multiple versions (that share the same major.minor version) may not work if dependencies have been introduced in the meantime. e.g. HBASE-29797 can be applied to 2.6.4 directly, but not to 2.6.3 as test libraries were introduced between those versions.