Retro Tablet Software and Hardware Upgrade

I am looking to hire someone to solve some software issues for me. I thought I could do it myself, but ultimately this project has proved to be much more difficult than I anticipated. The reasons for this primarily are that I didn't know as much regarding low level Android stuff as I thought I did. Mostly it has to do with some specific MediaTek issues and not being able to find the source code or information, and Ultimately if I had that I could probably work through it eventually, but as it is I would really just rather hire somebody to take care of it so it is done right.

I really like retro devices, kind of like taking an old Atari 2600 and put a raspberry Pi compute module 5 in it and playing retro games on it. So my most recent project is along that line. It has 2 GB of PCDDR3 RAM and 32 GB of eMMC storage, which is running at 32 bits. This is a pretty underwhelming tablet, but it's got a nice screen and unless you're trying to do a whole lot on it actually runs pretty well. I'm mostly a hardware guy so the first thing I did was promptly upgrade the eMMC to 256 GB, an increase the RAM from 2 GB to 4 GB (the extra 2gb of RAM not being recognized because this is hard coded in the device). What I didn't know was that the software that comes with it is a bastardized version of Android 8.1 and it just sucks. For me, rooting the tablet wasn't all that difficult, so it works just not as well as it could, but fixing the boot loaders and such has proven to be beyond my ability. The possibility of using bootloaders or preloader from another device seems remote since this device uses DDR3L (PCDDR3) rather than the more common LPDDR3 most devices of this class use, so substitute preloaders simply fail at the RAM initialization process. This is a nice little tablet I just want it to have better performance. I decrypted the user partition and saw a huge increase in performance, so overall I would like to take all of the encryption, secure boot, anything like that off of this version of Android, and if possible create a TWRP style recovery. Not only does it not need to be secure, I don't want it secure, I wanted as open and easy to operate as possible.

So, what I would like are two things.

1.) New (TWRP if possible) preloaders, bootloader's, and LK, LK2 for the Android 8.1 software I have.

2.) A completely new versions of Android that is 64 bit, addresses the full 4gb of RAM, and is at least Android 9 or higher.

I don't have any problem paying someone for their time, I just want it done right, and doing it right has proven to be beyond my own abilities. The hardware is right, I just need the software done.