If you take a closer look at the hardware specifications of the TIM Hub and try to find something similar within the stated budget you probably will be hard pressed to come up with a match. That box is really not bad at all, afaik:
- Broadcom 63138 Dualcore-CPU (incl. VVDSL & SVVDSL SoC),
- USB 3.0 Ports
- WLAN: 2,4 GHz 2x2 MIMO, 5 GHz: 4x4 MU-MIMO,
- support for Vectoring-VDSL2 & Super-Vectoring-VDSL2 (Profil 35b)
- SFP cage/port
If not mistaken the firmware used to be based on OpenWRT 15.05 Chaos Calmer. Not sure whether the ISP leverages own patches on the firmware but the TIM Hub might work with OpenWrt. If does it may however violate service/support/warranty stipulations with the ISP.
If the TIM Hub can be configured to pass through the traffic with upstream and the downstream node to handle everything else there should nothing be compromised.