D'oh! I did indeed forget about the video transcoding benefits of the T2.And I think it's the A2 chip that handles a lot of the HVEC encoding, so not sweating that.
All I know is my mini feels like it trudges through Handbrake queues rather than plows or glides. 😆 However, I must say, my 8th generation quad-core i7 equipped HP laptop doesn't exactly leave my mini in the dust with transcoding via Handbrake either -- but then again it is an ultra-low-power chip (i7-8550U).
Anywho...
I'm sure no matter what you upgrade to, it will be a significant boost, especially if you drop in 32 or 64GB of RAM.
P.S. I don't know where you call home, but beyond checking the Apple Store refurbished section, I recommend looking through ExperCom. They typically have at least small discounts on Apple's MSRP, deep ones for aftermarket upgradeable components, plus only charge sales tax to residents of Utah -- as far as I'm aware -- (where their brick and mortar stores are). I don't have any affiliation, just good experiences as a customer.