Uli Jon Roth had his Sky guitars which had 30 frets or more.HOWEVER
, the natural range of a standard 6 string guitar is 3 octaves. E to e is 2 octaves and a standard 12th fret neck join makes the 3rd octave.
Mathematically, it is perfectly possible to goto as many frets as you like, some of Uli's guitars got to 3 octave fretboards (although the highest frets were full tones rather than semi-tones and the fretboards were scalloped to allow him to reach the intervening semi-tones).
With all stringed instruments you face the issue of inharmonicity. Essentially, it means that the harmonics of the note are increasingly sharp relative to the fundamental as you go up the neck. And the problem is with how the mind processes those differences. there comes a point where the harmonics are so sharp that the brain perceives the fundamental as sharp.
If you really want to get to such a high note on a guitar I would suggest a different approach...
Instead of a 29 fret guitar look at a 7 or 8 string guitar with the extra one or two strings tuned higher than standard tuning instead of lower. Say, a set of 11's with a 9 and a 7/8 for the two extra strings.
Anything else and you are fighting a losing battle against the laws of physics and material technology.