We are already indirectly using much larger numbers with the concept of Cosmological Decades, which is a time scale that maps out the future life of the universe.
In a general sense, magnitude is not important in terms of causality. If things are small or big or bigger or immense is neutral in terms of causality of universal processes.
The scale we can comprehend or describe those processes is unlimited and unimportant.
All true, but we still like to name things. As long as we continue to use fundamental units that seem reasonably sized for everyday life (e.g. kilogram, meter, second), we’re going to need a wide array of prefixes to create much larger/smaller units to gracefully deal with the extremes we encounter from time to time.
Occasionally it’s necessary to abandon standard units altogether, although this only seems to be commonly done in astronomy.
At the other end of the scale, the only alternate unit I’m aware of is the barn, which describes cross-sectional areas relevant to nuclear reactions. It’s 10[sup]-28[/sup] m[sup]2[/sup], a fraction of a square meter that doesn’t have a conveniently available prefix.
To the OP’s question:
It’s hard to say yes with absolute certainty, but we’d be foolish to say no with any certainty. There isn’t a correlation between Avogadro’s number and how fast a computer is, so there’s no reason to expect similar limitations in speed/nomenclature.
And in high energy physics we commonly use femtobarn which stands for 10[sup]-43[/sup] m[sup]2[/sup]. Ideally we’d have chosen an even smaller unit than the Barn. As Wikipedia says, some have tried to make up for this by coining the terms outhouse (10[sup]-34[/sup] m[sup]2[/sup]) and shed (10[sup]-52[/sup] m[sup]2[/sup]), but they haven’t stuck :(.
The barn is of interest because it names a unit that’s far beyond the existing range of commonly used prefixes.
Where the Ångström is concerned, there are smaller SI units that use standard prefixes, like the picometer (10[sup]-12[/sup] m) and the femtometer (10[sup]-15[/sup] m).
No idea. It’s probably the preference of the cosmologists that came up with the definition. This letter was used in old English and/or Scandinavian languages.