  Cryogenic calorimetric experiments to search for neutrinoless double-beta
decay ($0\nu\beta\beta$) are highly competitive, scalable and versatile in
isotope. The largest planned detector array, CUPID, is comprised of about 1500
individual Li$_2^{100}$MoO$_{4}$ detector modules with a further scale up
envisioned for a follow up experiment (CUPID-1T). In this article, we present a
novel detector concept targeting this second stage with a low impedance TES
based readout for the Li$_2$MoO$_{4}$ absorber that is easily mass-produced and
lends itself to a multiplexed readout. We present the detector design and
results from a first prototype detector operated at the NEXUS shallow
underground facility at Fermilab. The detector is a 2-cm-side cube with 21$\,$g
mass that is strongly thermally coupled to its readout chip to allow rise-times
of $\sim$0.5$\,$ms. This design is more than one order of magnitude faster than
present NTD based detectors and is hence expected to effectively mitigate
backgrounds generated through the pile-up of two independent two neutrino decay
events coinciding close in time. Together with a baseline resolution of
1.95$\,$keV (FWHM) these performance parameters extrapolate to a background
index from pile-up as low as $5\cdot 10^{-6}\,$counts/keV/kg/yr in CUPID size
crystals. The detector was calibrated up to the MeV region showing sufficient
dynamic range for $0\nu\beta\beta$ searches. In combination with a SuperCDMS
HVeV detector this setup also allowed us to perform a precision measurement of
the scintillation time constants of Li$_2$MoO$_{4}$. The crystal showed a
significant fast scintillation emission with O(10$\,\mu$s) time-scale, more
than an order below the detector response of presently considered light
detectors suggesting the possibility of further progress in pile-up rejection
through better light detectors in the future.
