We present a MgO:PPLN- and AgGaSe2-based, picosecond OPG/OPA scheme, enabling the generation of mid-to-long-infrared continuously tunable, microjoule energy pulses with a narrow spectral bandwidth of sub-8 cm-1 over the full tuning range. The approach combines a 1-µm-pumped, double-pass OPG setup with a 2-µm-pumped parametric booster amplifier stage. As pump laser is applied a CPA-free Ho:YLF laser delivering 32 µJ at 2051 nm wavelength and 20 kHz repetition rate. The OPG/OPA system specifications of µJ-level pulse energies in combination with narrowband and widely tunable, mid-to-long-IR spectra enable numerous possibilities for mid-IR spectroscopy and wavelength-specific mid-IR material processing.