I heard some claims that CTV needs 3 other opcodes to do LN-Symmtery. That’s wrong.
LNhance is CTV + CSFS at it’s core and that is enough to do LN-Symmetry.
IKEY and PC are tiny composable pieces that optimize the use of CTV and CSFS for LN-Symmetry.
There are several ways to solve the data availability problem, some don’t even require a consensus change. Some don’t even require a relay policy change.
LNhance is just the best way of doing it that we know of.
edit:
One way to think about the 3 opcodes (CSFS, IKEY, PC) is we decompose a CSFS variant that can use 1 byte pubkey (internal key) and can commit to a vector of stack elements as message. They thus become more generally useful, but to a limited degree without additional opcodes.
Detailed introspection opcodes would also need vector commitments with CSFS, and it would also be useful for OP_CHECKCONTRACTVERIFY aka CCV.