Overview

The sideways thumb was suggested as an emoji to the Unicode Consortium and was subsequently declined (according to https://www.unicode.org/emoji/emoji-proposals-status.html).

Goal: get enough signatures to demonstrate that there is a (sufficient) demand for a sideways thumb emoji – and, subsequently, resubmit the idea to the Unicode Consortium for reconsideration.

Who is affected?

Anyone and everyone who includes emojis in their textual communications – particularly, those who wish to express the idea of neutrality or "being mid".

Motivation

I, and some of those I am acquainted with, find that, sometimes, a sideways thumb emoji would best convey our messages. — When writing, I have found myself in situations where a thumbs up, thumbs down, and OK (both in hand-sign-form or word-form) is inadequate, as I want to convey something is "meh" or "just alright".
While "OK" could read as meaning "meh", "neutral", or "just alright", it could be seen in a slightly more positive light, as in "This is pretty OK!" — in other words:  how enthusiastic the "OK" sounds affects whether it has a neutral or positive (or even negative) connotation, which is not something that can be inferred by text/emoji alone.

Additionally, a comparable concept can not be represented by placing any two currently existing emojis together – and trying to combine more would make reading and writing such sequence pointless, as emojis are ideally a one character per some number (X) of concepts greater than or equal to one (1:X char/idea).

According to the Emoji Proposal Status document, maintained by Unicode Consortium – the organization that maintains and regulates emojis, as well as other standards relating to digital text – the idea has been proposed already but has been declined;  however, there is no explanation as to why it was declined — moreover, a document, Gesture Emoji for Consideration, Unicode 15.0 – published november 2020, two months after the (now declined) proposal was submitted – stated that it was rejected because (they are) “unclear if associated meanings are sufficiently common use”.

(Flagship) Meaning

The flagship meaning of (a) sideways thumb emoji – possibly also referred to as a "thumbs-to-the-side emoji" – would be "meh", "neutral", "indifferent", et cetera.

According to Gesture Emoji for Consideration, Unicode 15.0, the closest match (emojiwise) is '😐' ("Neutral Face"), which may be true in some contexts; however, I may want to put a sideways thumb next to a frowning face (or a smiling face), in which case, the meaning of the neutral face (or the smile/frown) would become confusing, as it would probably be read as trying to combine a neutral expression with another one.

Additionally, there is also a shrugging emoji, which is the closest in meaning;  however, in addition to meaning "neutral" or "indifferent", it could be interpreted as "I don't know (yet)", which may not be the message you mean to convey.

Other (Potential) Meanings

I am not sure if these other suggestions were part of  [a / the]  previous proposal, or if Unicode Consortium thought of them;  however, Gesture Emoji for Consideration, Unicode 15.0 lists two other possible meanings for a sideways thumb emoji:

1. Hitchhike / "Can I get a ride?"
2. "this person"
      (In addition to meaning "this person", a sideways thumb could be used as another, generic, way to point at some text or other thing.)
3. In combination with the baby emoji  ('👶'), it can mean "baby sucking (their) thumb".

While I would not personally use the emojis in these ways – save for some exception circumstance(s) – I can certainly see how it could be used that way and why people would want an emoji for these concepts (as well).

Closest Match

'🤷' ("Shrug")

Suggested Name

Sideways Thumb

(Named as "Fist With Thumb Facing Sideways" in Gesture Emoji for Consideration, Unicode 15.0.)

Conclusion

With the consortium updating the Unicode Standard on an annual basis, and having added thousands of emojis since their addition in 2009, I believe it's high time to introduce the sideways thumb emoji, since it was declined for reasons unspecified.

The objective of this petition is not to question or undermine the consortium's authority or decisions over Unicode – a standard they own and maintain – but there is a gap in (the existing spectrum of) emojis.