iPhone 11 Memory Full

I found you in a google search – you seem to be the best people who could help resolve a dilemma I’m having with my iPhone 11, in that it’s stuck on the Apple logo reboot loop. (https://www.dataclinic.co.uk/recovering-data-from-iphone-error-1110/)
It’s pretty much full storage, which is why it’s crashed, and why the steps to put it in recovery mode and updating software or bypassing it on iTunes do not work, on top of force restarting it. It may have got damp in my bag – only slightly, if at all, but this was shortly after it went into a reboot loop.
The crisis is that I cannot by any means restore my phone – due to some extremely precious and invaluable application data (TikTok) which is stored locally to the device, and would 100% be lost if the app is uninstalled, let alone restored. This data isn’t stored in the cloud or a server, only the device.
I believe there’s around 9 GB of this data.
The storage on my phone was 63.6 out of 64. Deleted a huge amount from iCloud but it had not synced before it crashed.
I’m pretty sure my photos are backed up to iCloud, however this particular local storage is what’s causing me grief.
Before finding your service, I was about to find someone with a Windows computer to use a program called ‘3uTools’ to try to break into the phone without any data loss.

Recover Pixel phone

My google pixel 4 has suffered from a ‘motherboard failure’ on the 27th of july – I had it assessed by 2 phone repair shops who have both come to the same conclusion, and both say the motherboard seems in good shape visually (ie no water damage), see https://www.dataclinic.co.uk/android-data-recovery/
I wonder how easy would it be to recover data from it? If I plug my phone into my PC, the PC does recognise that there’s something (but it’s a random sequence of digits..) and I’ve tried using Wondershare Dr.Fone to see if it can recover anything, but I never turned on OSB debugging so I can’t access anything on my phone.
I wish to recover my local whatsapp backup specifically – I have the rest of my phone backed up, but I messed up with synchronising my whatsapp when I set up another phone.
Any guidance and an idea of cost would be much appreciated!