Yes; can be done on the Note8. And should be done.
A lot of folks ask... why?
Well... why do people tweak for more HP out of their already powerful cars with NOX and stuff?
Why do some overclock their PCs; beyond the requirements of the most demanding games?
Why do people build their bodies into proportions/strength not required for everyday living?
Why did they climb the Everest?
Well... to push the limits, to conquer higher numbers. To be high specced.
To seek superior performance and capacities. To raise the bar from "can't-be-done" to "what next?"
Yes; the Note 8 is very expensive. But that should not be a deterrent to take the specs of this marvellous device to still insane heights.
And, proceeding with caution, the phone itself remains safe althoughout the hack process.
That risk will be on the SIM, and mostly on the mSD card.
Even if for just bragging rights, I think within the limits of reason, such attempts should be made.
Even if just as a proof of concept.
So, below is how I now have a DeepSea Blue 256 GB Note 8 running two SIMs and a 128 GB SD card; all together.
No rocket science involved. Just preparation, patience and fine handiwork.
Plenty of YouTube videos on the matter; so I'll just add what they may have omitted and also some specific things for doing the hack on the Note 8.
In addition to the usual tools, I found the following helpful.
Well illuminated work-space and a black background to work with (T-shirt?)
Iso-Propyl alcohol wipes (local pharmacy)
Emery paper nail files (raid your wife's or daughter's beauty kit

)
A tooth pick
PVA glue (also called craft glue)
Reading glasses - go get one (I had found one someone forgot in a shopping cart- a +1.5 one with own built-in LED lights)
and a strong cup of coffee under your belt; no distractions.
Start with the SD card; remove the "bump" first and then file down the labelled side.
Manual filing will tend to deplete the edges more; so check regularly. Work on the middle to make it uniform flat.
Take it slow; clean with IPA wipes every so often and check the card carefully.
When held with the labelled side facing you, and the grooved edge on your right, be aware that the actual memory chip will be on your bottom left (you can file away more vigorously elsewhere).
Many careful minutes of filing later, a coppery silhouette of the memory chip will emerge on the card. From hereon, be exxxtra careful not to remove too much material. File away until the silhouette is a coppery rectangle (without the actual metal showing).
Now, file the SD card edges to make the top and bottom (when held as described earlier) rounded. This will greatly reduce the chances of the card snagging in the phone's hybrid tray later (it can slide out better)
Needn't file the other side- it's metal right underneath. Damage risk too high.
Clean it gently and thoroughly with an IPA wipe, test if it still works and set aside.
Place the intended SIM2 in the Hybrid tray. Make four marks with marker pen on the tray, of the exact corners of the golden SIM chip contacts. Also mark the SIM chip where the SIM'S bevelled side would be (scratch with tweezer's point; pen mark will vanish when cleaning)
Now, use mild to medium heat and remove the SIM chip from the plastic substrate (lighter flame and tweezers will do fine).
Clean it up with IPA; remove any gum residue. Set aside.
Place the SD card as designed on the Hybrid tray; superimpose the SIM chip on it with the scratched edge aligned properly (as it would do if on the SIM card). Does it fully fit? If not, trim off the excess very finely with scissors (most SIM cards fit well without trimming).
Now, with the SD card in the hybrid tray, use the toothpick to place just a minuscule droplet of the PVA glue on the SD card (using PVA glue, the mSD card be separated from the SIM chip in future more easily- if so required-, compared to superglue. I won't recommend two-sided tape as we want minimal thickness). Place the SIM chip correctly and with all corners aligning to the earlier made marks on the hybrid tray. Manoeuvre the SIM chip, pushing it down with the other end of the toothpick, to align everything near-perfect. Let the mSD-SIMchip combo dry for 20 minutes (can use a hair-dryer) and then try loading everything into the phone, along with SIM 1. Should you feel a small resistance, slide the tray back and forth... get a feel. You then get a reading of the tightness, and can proceed with fully inserting the tray- yes; it will still be very slightly tight- but that will be OK. Ensure the phone reads the two SIMS and the SD card simultaneously. Then eject and reload the tray one more time, and when it does.... voila! you have succeeded.:victory:
You have hacked the Note 8 dual SIM to run a simultaneous mSD card. You have raised the barrier, hacked the device to better specs. :highfive:Now go, have a beer and rejoice with your phone. Show it around to a few mates.
And keep pushing the boundaries of what's possible.:good:
Regards