[General Questions and Answers] SubwayChamp:
Exactly, a lower version is always less secure. It typically ever happens, an exploit is found by the community then Samsung aware of and releases a patch in the next binary.

I owned some months ago the J7(6) that was very easy to root it, the main con was that this device have the speaker in the back and it really sounds horrible.

Now I have the J7 Pro (7) (SM-J730G) and although I read many warnings in various sites it was nothing hard to root it. If you are referring to the J7(8) there´s not much difference in hardware capabilities with this (Exynos 7870 vs 7885 if I´m not wrong) so if you can grab a similar model it should be a good deal of course 22 bucks it´s a very low price.

I´m not sure why there is not development for this device if it hasn´t bootloader locked by carrier so J7 devices have a sort or cross development and high compatibility between various of them. I´m likely sure that this TWRP can work so the main difference probably is in the modem/radio. BUT probably it should be needed to edit the properties about model and product at getprop and fstab (if this last is present) to get it compatible.

If you are in Oreo first of all I should do is to check that in Download mode screen the RMM state is normal, in the case of it appears like prenormal then you should have to wait the period time or go to the Samsung Account that I linked to disable this state, this way the worst that can happen will be a device soft bricked but with a download mode accesible to the user BUT in the case that this state be ignored then you know that FRP/RMM/KG can be activated and this should do the things worst. The zips that I linked also are to be flashed through TWRP to bypass RMM state, v2 is for oreo and v3 is for Pie.

The steps that I did were;

- Flash TWRP through Odin unticking Auto reboot, then to finish reboot manually to it (you need to be very carefully in this step, if device try to boot to system before to can flash DM-Verity then the alerts will be activated.

- Second step once in TWRP I should flash DM-Verity to bypass AVB/boot secure.

- Reboot (without root it yet) In my case I just need these steps without need of flash anti-defex.

- Then go to TWRP again and root it either with Magisk-Defex or Magisk normal starting with v19.3 and then from here you can go updating it under requirement from within Magisk itself. Defex doesn´t imply an issue to reboot to system just interferes within a rooted status and the apps to short circuit within both so the apps can´t properly get root access. What Magisk-defex does is at same time to root it provide a way to communicate with apps so the access can be granted.

As a side note I should say you that since many users don´t care or don´t know about the last account linked onto device they simply format data thinking that it is all that a new user needs to get a fresh start but before to format data is recommendable that the last user sign out from the old account and then surely you can proceed to format it otherwise the old user will have a remote access to the device and they can erase it and also more actions will be accesible for they, in the case they opt to do it, this is one of the things that active the FRP status.