If I recall correctly, there are only three profile zones for VDSL2 (Annex A, North America; Annex B, Europe; Annex C, Japan) and some even contain compatible profiles. I would guess that Egypt would use AnnexB so an international version might not be required....
I concurr with @frollic in all likelihood not. Also telephony will likely not work on OpenWrt either. I bought a gigaset* VoIP base years ago, when I wanted to get independent of my ISPs all-in-one VoIP router combo.
*) Which works OK and only supports DECT phones, I am sure other brands works fine as well, that is just the only one I have first hand experience with; however one can also use a stock fritzbox as VoIP base station behind an OpenWrt router, probably what I would do the next time around given that FBs can often be gotten second hand for little money.
I expect VDSL2 to be usable in Egypt, but if not, you can use one of the switch ports as WAN as well (but that has sometrade-offs, so is not ideal).
After you flash OpenWrt both models will be essentially idenyical. ATTENTION though, there is a newer model of the 7520 (without the two fin-like antennas on the top of the case) that is (currently?) NOT compatible with OpenWrt as it does not use a lantiq/intel/maxlinear DSL chip at all...
The Fritz!Boxes are fine as-is, with the OEM Fritz!OS firmware, for the telephony needs behind your OpenWrt router (in IPoE mode, doing only VoIP/ SIP and acting as SIP pbx, ATA and DECT base). But using it this way would require a(nother) VDSL modem, a wireless router running OpenWrt and the Fritz!Box for the phone needs.
OpenWrt can drive them as modem and wireless router, but has no support for their telephony hardware features.