IIRC, many 'legacy' mobos may be upgraded to Win_11 support by adding a plug-in 'Trusted Program Module' (TPM). Buys a couple more years for hardware...
Snags are header-types vary, and there's a bit of confusion at present due a lot of TPMs using Chinese chips: YMMV...

Firefly, so CPU-only renders ?? Yes, get lots of nimble cores, the more the merrier...

Uh, do Firefly renders use 'Render Queue' reliably ? If not spending fortune on bleeding-edge GPU card, you may be able to split your budget to get a multi-core, basic GPU, network-render 'Box' to supplement your main system. Set up your scene, check with 'fair' resolution local render, increase resolution and send job to 'Box'...
Next ??
;-)