Cable prices are all over the map and the reason super overpriced ones exist is because people buy them unfortunately.
I have used these cables for years now and they work out to be $10/ea.
I have a 75 U7G and a Series X. I play COD Warzone and every game in 4K HDR 120Hz VRR. I have zero issues. Never seen any flickering. No audio delay. I use ARC to my Onkyo TX-NR809 and have the Xbox bitstream DTS for games and passthrough Dolby Digital+ for videos. My AVR is not Atmos capable.
I use these HDMI cables as I needed longer ones since they are hidden behind my wall.
I wonder if the issues you are experiencing are HDMI bandwidth issue. I hope when my Onkyo RZ50 arrives in December I'll be able to use Atmos without problems.
By the way DV gaming doesn't work because when the Xbox sends DV 60Hz to the TV during games the TV goes into DV picture modes and Instant Game Mode is blacked out and cannot be enabled and the input lag is unbearable
When you say another stack running concurrently, you just mean using one BT adapter for one device at my TV while having the other BT adapter at the computer (not even connected to anything), right? Here is a diagram of what I'm trying to do with BT: https://imgur.com/a/34MJFfb
When I first started testing the HDMI extenders, I actually went straight to the wall (so like, about 110 ft of Cat5e with multiple couplers) and it seemed fine, but they were probably doing some chroma subsampling (like 4:2:0) that I just didn't notice in order to get the signal to transmit the 4k/60hz TV. I DID verify 4k/60hz & 8-bpc though and honestly it looked fine and had no latency (tested with Dark Souls and wasn't getting my ass kicked haha). My TV can only do HDMI 2.0 (not 2.1) so even if I could find a better HDMI extender (I can't), that's my currently limit.
So if you just wanted to use what was in your walls, then you could reasonably get by with that and be happy.
FYI, here's what I use (and am testing)
USB over Ethernet Extender: https://www.amazon.com/dp/B08HHFZY5H - works great!
USB Hub: https://www.amazon.com/dp/B00PHPWLPA - works great!
HDMI Extender #1 (currently using): https://www.amazon.com/dp/B07Q23PLBB - eh, seems fine. I don't use its "Local" port because then it tries to copy the TV resolution to my local monitor and I think it overloads the balun. Not convinced this isn't compressing my AV signal and losing data (e.g., chroma subsampling) because they confirmed it doesn't use HDBaseT. It's made by Cable Matters (Chinese AV company) - same as my USB stuff. They're alright, I also use their Ultra Speed Certified HDMI cables (48 Gbps): https://www.amazon.com/dp/B084RFQPSP
HDMI Extender #2 (bad): https://www.avaccess.com/products/4kex60-h2/ - I tried this and it crapped out after a day. They told me to swap it for their 4KEX70-H2 because the 70 uses HDBaseT, but I don't trust them anymore and am just going to return this. Another Chinese company (AV Access) and they are being difficult about returning the product.
HDMI Extender #3 (haven't tried): https://www.amazon.com/dp/B079PMQSZ8 - I might try this next because it's an American company (Orei), but they make the same "Cat5e/6 UTP" claim along with HDBAseT, which shouldn't be right, so I'll see what that's about.
Any other reputable AV company (Crestron, Kramer, Comprehensive Cable, Hall AV, etc.) will make these or fiber-optic HDMI cables but the extenders can literally be over $1,000 and the fiber-optic cable will be $400+. That's why I went cheap over Amazon. There are some fiber-optic HDMI cables there too (again, cheaply made), but I figured I'd have more reliability with an extender than single, expensive cable running through my Texas walls.