It appears that the following seven small kana were accepted in UTC-149:
HIRAGANA LETTER SMALL WI
HIRAGANA LETTER SMALL WE
HIRAGANA LETTER SMALL WO
KATAKANA LETTER SMALL WI
KATAKANA LETTER SMALL WE
KATAKANA LETTER SMALL WO
KATAKANA LETTER SMALL N
Essentially, the small forms of the following characters will eventually become available: ゐゑをヰヱヲン. Strangely, small ん was not accepted, further reinforcing the gap between the katakana and hiragana writing systems.
All things considered, I think this is a good step forward, but at the same time, it's hugely disappointing that no further consideration was given to the other characters proposed and that zero consideration was ever given to the Ryukyuan languages. Several of the characters in the L2/16-354 proposal (linked in my first post) would have been beneficial to transcribe the Amami and Miyako languages and their dialects, especially small む to mark an /m/ sound and small す to mark an /s/ sound (personally, I would have also added small ず and maybe small ふ to cover additional characters that are often used in transcriptions of Miyako, but that's an aside).
The extremely slow adoption of small kana reminds me of Unicode's decision to incompletely implement Latin superscript and subscript symbols (https://en.wikipedia.org/wiki/Unicode_subscripts_and_superscripts#Latin_and_Greek_tables ). Maybe, just maybe one day we'll get them all.