My definition of the smallest Astronomical Telescope is
1. Larger than 3 inches(76mm) in aperture
2. Better than 1/4 pv wave or 0.8 strehl optical performance
This exclude telescopes with central obstructions of 33% to 39% of diameter.
Those with higher obstructions is normally sold as spotting scope or Astrograph lens or mirror.
The largest Commercial Eyepiece as of 2014 is taken from forums
31 Nagler 2.2 lbs
21 Ethos 2.25 lbs
30mm ES 82 degree 2.2 lbs (newest version)
30mm Meade Series 5000 UWA: 3 lbs
31mm Celestron Axiom LX 3.1 lbs