Upgrading a Mac Pro 5,1 options

In summary my question is - is it possible and worth upgrading any further?

For those who straight off say don't bother, buy a newer mac, my reasons are that I have on older firewire interface, and a couple of internal storage drives, so I would have to replace these with external adapters and drives if I bought a s/h 2013 trash can, and would then have a bit of a messy desktop. I like the fact that the the early Mac Pros are just tin boxes that you can swap out components in easily.

I currently have an early 2009 Mac Pro 4,1 that had a firmware update to make it act like a 5,1, and I replaced the GPU with a Sapphire AMD Radeon HD 7950 mac edition so it can run Mojave and added a SSD from OWD as the main startup disk. The system reports the CPU as 3.33 GHz 6-Core Intel Xeon W3680 single processor. It has 16GB 1333 MHz DDR3 memory.

I was wondering whether it would be possible to do the following:

add another/upgrade the processor

increase the amount of RAM

Run the micropatcher and upgrade to Big Sur

Anything else that would extend the life of this machine.

I don't do video anymore but do use music software like PreSonus Studio One, Ableton Live etc. I don't have latency issues. I might need the storage space if I decide to get into video again.

My main issue is Apple's lack of support and being stuck with Mojave (not that there's anythng wrong with Mojave, but some newer software requires a newer OS). It would be great to have the power of a newer mac in the shell of the 2009.

I don't mind getting my hands dirty. Are there any options or is it really not worth the bother?