The high energy electron experimental platform * at ELI-Beamlines will give to the users high energy tunable electron beams with low energy spread and divergence, by employing laser-wakefield-acceleration scheme (LWFA) driven by PW-class laser system working at 10 Hz. The platform will offer great flexibility over electron beam parameter space and is foreseen to exploit different targets, acceleration and laser-guiding advanced schemes. In this paper we summarize about more compact accelerators that can be envisioned by the use of really short (near single-cycle) fem-mJ-level laser pulses interacting with nanoparticle and solid targets, as well as with specific near-critical density targets. * Originally developed as H.E.L.L., within the Particle acceleration by Laser program (RP3).