I have a laptop which requires Linux kernel 5.10 for the GPU, and 5.11 for the WiFi/BT
What is Zorin OS 16 coming with? Is it possible to upgrade the kernel at all in Zorin OS to these versions, and lastly, if it is possible, how could one PRE upgrade the kernel prior to install.
Live boot wont work of course due to mentioned items above. Only Linux distro's I have been able to get work are ones based on 5.10 and up.
The simplest method I can think of would be to download all four required packages to upgrade the kernel. Save them to USB (either the same one with Zorin on it or a separate one). Install Zorin, then once the installation is complete, reboot. Upon opening the desktop, immediately install the later version kernel you downloaded and saved to USB earlier.
If you save it to the same USB Zorin is on, just reboot, plug in the USB and mount it to Browse the files, then install them using the terminal.
Open the terminal in the directory your .deb kernel packages are in.
Use sudo dpkg -i <PACKAGE-NAME>.deb to install each. If you get a dependency on one of the other kernel packages, just install that other one first.
This way you avoid trying to replace the kernel call in the ISO you burned and also avoid needing to use WiFi or LAN right at the outset and can get the kernels installed quickly.
Then reboot and test.
problem already encountered 
Installer wont display anything due to pre 5.10 kernel which Zorin 15.x comes with
Zorin 16 comes with kernel 5.8.0. So far, anyway...
Can I ask you to clarify this? Even the newest machines still should be able to open and run on older kernels. There may be more teething troubles for some.
Are you using integrated graphics? A dedicated Graphics card? Nvidia?
Sure, I have a Dell G5 SE laptop with a 4900H APU and 5600M dGPU.
Neither are supported or display anything unless running Kernel 5.10 or higher.
I have tried about 20 different disto's now, and confirmed that those with kernels BELOW 5.10, simply do not display anything after selecting install/live/etc, Manjaro and other distro's based on Arch latest work without issue.
AMD Radeon 5600 - should be supported by kernel 5.6.0, which does not come with Zorin 15. However, the soon to be released Zorin 16 may well support it.
However, while the latest kernel includes a patch, the proper Graphics Drivers can be installed to run Radeon 5600M on Zorin 15, Ubuntu 18.04 or Ubuntu 20.04.
The downside is you would need to boot in nomodeset to get installed. You would need to tolerate some low quality graphics until the installation is complete, then install the drivers.
As to why you had more luck with Manjaro and Arch- I suspect it is because they place more emphasis on included the drivers or higher kernels. For a broad audience, jumping to the latest and highest kernel can cause a lot of issues on older computers and many distros prefer to avoid that conflict.
To boot into nomodeset from you USB media, please see this guide here:
https://medium.com/@peterpang_84917/personal-experience-of-installing-ubuntu-18-04-lts-on-xps-15-9570-3e53b6cfeefe
Unlike Nvidia, Radeon is supportive of open source and outsources their drivers.
Which is how they are included in the kernel. You may prefer to upgrade your kernel to the higher version after completing the install, rather than messing with the drivers.
That will probably be the case, I also installed an Intel AX210 and that required kernel 5.11 to work properly. I tried to install just the drivers on 5.10 but that still didnt work and I find only posts where kernel 5.11 resolves the issue.
I look forward to testing Zorin OS 16
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