Emojis with quail - but only some

Hello,

my goal: I want that hitting : starts the input of an emoji, so that
:+1: would insert 👍.  Without the need to hit one additional key.

This is exactly what the "emoji" input method does - but it does much
more!  For example, writing "dog" would insert an Emoji of a dog.  I
don't want that in general.

Defining a new, restricted version of the "emoji" input method doesn't
seem to be trivial.  And I don't want to copy half of the definition of
the input method to my config.

I then thought: ok, let's bind : to a command that first enables "emoji"
as transient input method (`activate-transient-input-method' - I don't
want to call this command explicitly btw. although this would be a
workaround - I know!), and then simply invokes `self-insert-command'.

Well, I don't get it work: either the input method doesn't recognize the
: as input, or, when I use `unread-command-events', I get interference
effects that make Emacs unresponsive.  Weird effects, hitting the cursor
keys moves the inserted : around, infloops, such things.

Any suggestions?  Or other practical ways to get a similar
functionality?

Bonus points if somebody can suggest a way to make :? (a question mark
after the colon) would call `emoji-insert'.  Normally I would use a
transient map for that but I'm not sure if that would not also interfere
with quail which probably uses something similar.


TIA,

Michael.