[Android Q&A, Help & Troubleshooting] balyztik:
For those with the same device, I was able to successfully root + pass safetynet, without TWRP or custom recovery. Since this device isn't yet on the forums I thought I should share my findings.

At the time of rooting, I was currently updated to the newest version available (10) and did this through the regular OTA updates.

Preparations

1. Download Magisk Manager Beta from https://magiskmanager.com/magisk-beta/

2. Download the stock firmware for your tablet from https://mirrors.lolinet.com/firmware/lenovo/Yoga_Smart_Tab/YT-X705F/

3. Download kdrag0n's SafetyNet Fix from: https://github.com/kdrag0n/safetynet-fix/releases

Edit: looks like I missed a step, thanks for the feedback! Point 4 has been corrected to include instructions on how to unlock the bootloader specifically.

4. Unlock your bootloader, instructions on how to enable USB debugging which is needed, can be found here: https://www.shizhub.com/2018/12/how-to-enable-disable-usb-debugging.html, from there you can open your command prompt, navigate to the directory where you have your fastboot and ADB stored, and type "adb devices" to confirm your device is found (a serial number will display on success) - next type "adb reboot bootloader" to force your tablet to restart into it, finally type "fastboot oem unlock-go" to unlock the bootloader.

This voids your warranty.

-- end of edit.

5. Enable USB debugging through developer options (go to settings->about->find build # and tap a handful of times until it says you are a developer.

6. Plug the tablet into your PC, and set the default option to Charge only, or go to file transfer mode and enable USB debugging over file transfer.

Steps

1. Unzip the firmware, there should be a folder called Maincode, in it contains "boot.img" as well as adb/fastboot.

2. Copy the boot.img and Magisk apk to the tablet.

3. Install Magisk

4. Tap on "Install" or "Update" beside Magisk in the app and follow the prompts.

5. You will be asked to select a file, select the boot.img you copied earlier.

6. This will generate a file (it will tell you the path) of a patched boot image.

7. Reboot, and copy the patched boot image to the "Maincode" folder from the tablet.

8. In command prompt, type adb devices and make sure your serial number is shown. If not, review the preparations.

9. Type adb reboot bootloader and you'll see a cute little Tux (penguin)

10. Type fastboot devices and ensure your device is shown, if not then it could be bad drivers on your PC or a crappy USB cable. Check device manager on your computer and make sure you see Lenovo ADB. You may have to force it to install it, or you may see a yellow exclaimation mark - right click on the device and force it to install the Lenovo Bootloader option.

11. Next, in the "Maincode" folder where you put the patched image, rename the old "boot.img" to "stock_boot.img" and the patched version to "boot.img"

12. Back in the command prompt, type fastboot flash boot boot.img

13. Reboot by typing fastboot reboot.

Magisk should now be installed, and your tablet should be rooted. Next, you'll want to go into Magisk and do the following:

Steps:

1. Click on the modules button (bottom of the screen, far right option) and at the top you're given an option to install from storage.

2. Navigate to the SafetyNet Fix zip file and select it, then proceed.

3. You will be given the option to reboot - do this. The first time it may go into recovery, but rebooting brings you back to the home screen.

4. Go back to Magisk, click on the gear at the top right - there is an option to hide Magisk from the system, do this and name it whatever you'd like (just not Magisk) - wait a moment, as the app will restart after it installs.

You can check to make sure you pass SafetyNet in the Magisk (now renamed) app, and root status by downloading one of the countless root checking apps on Google Play Store.