It is your DM's call if Simulacrum is eligible to store
You shape an illusory duplicate of one beast or humanoid that is within range for the entire casting time of the spell.
It is not explicit that the creature copied is the target of the spell. For this to be explicit would require the spell text to refer to the creature as the target for the spell, like in Polymorph, which says
The transformation lasts for the duration, or until the target drops to 0 hit points or dies.
Simulacrum never refers to the creature copied as a target, so it is up to your DM if he want this to work or not.
You can only copy a creature present during glyph creation
The spell description demands that the creature to be copied is within range for the entire casting time, that is during the time when you cast the simulacrum spell in the process of creating the glyph. So you can not create an instant copy of any random beast or humanoid walking by later on. If it were possible to store a Simulacrum, it would need to be of someone who is in range during the original casting.
What about the Snow-Form?
The material component of Simulacrum includes
Snow or ice in quantities sufficient to make a life-size copy of the duplicated creature
With a range of touch and a casting time of 12 hours ...
You shape an illusory duplicate (...) The duplicate is a creature, partially real and formed from ice or snow
Together this strongly suggests that during the casting of the spell, you are forming the shape of the copied creature from snow and ice with your own hands. You are not touching the creature copied for 12 hours straight, as explained in this Q&A.
How would this interact with the glyph? What's missing is the final transformation of your snow-object into a creature, as the spell finishes. What happens with the snow creature in the meantime?
Simulacrum states that if the Simulacrum dies
it reverts to snow and melts instantly.
This indicates that the snow material component is not consumed in the casting, it sticks around in the physical form of the simulacrum, and suggests the snow creature would need to be around at the time of the spell triggering. This means the physical snow-form would need to be preserved.
It is unclear if it would vanish magically until the glyph triggers, or if it would rest near the glyph until it is triggered. It is also unclear if it would be conserved in this state by the glyph, or if would need to be kept in a cold environment to not melt and possibly then make the spell fail. Nothing says so, so likely it would still be around, kept up by the magic of the glyph.
All of this is deep into DM interpretation/ruling territory, as is to be expected by combining two of the most ill-defined and complex spells in the game.