Can I create a lens that will function as a magnifying glass or spyglass with Minor Illusion by using the illusion as a focus to warp or bend light as a lens might?
Alternatively, can Prestidigitation create a spyglass or magnifying glass?
You create a nonmagical trinket or an illusory image that can fit in your hand and that lasts until the end of your next turn.
Permanently replacing these valuable objects is beyond the capabilities of these spells.
Minor illusion says:
I'd rule that magnification is an "other sensory effect", so this doesn't work. See this great answer for further details. Further, minor illusion stipulates:
It seems to me that because it is an illusion and things pass through it unimpeded, light would pass through the glass unmodified, so it would not function to magnify what you are looking at - magnification requires the light to interact with the medium it passes through, which is not how minor illusion works.
A spyglass is not a trinket. It's worth 1000gp. Examples of trinkets can be found on this table in the basic rules. None of these come even close to the value of a spyglass (their values aren't even listed - they aren't worth much at all).
This ruling is further supported by the Sage Advice Compendium when it says:
That's the closest thing to a RAW answer we have here, and I think it's pretty clear, especially with the explanation from Sage Advice. Further, there's a pretty clear (to me at least) sense in which these spells are not meant to create things of significant value, and magnifying glass and a spyglass are valued at 100 gp and 1000 gp, respectively. Why does this value matter? A cantrip than can be cast at will with no cost serves as a functional permanent replacement for these items if they are allowed to create them.