Plenty of ways. Strapping a CPU heatsink isn't the simplest due to the differing hole spacings between common CPU coolers and GPUs. Certainly possible. Might look into modding a Noctua NH-L12S, be quiet! Shadow Rock LP, or Scythe Shuriken on there.
Kraken G12 and Asetek style AIO? Designed for GPU cooling, and certainly compatible with reference GTX970.
https://www.amazon.co.uk/NZXT-KRAKE...d=1&keywords=kraken+g12&qid=1623268878&sr=8-1
Just add AIO. Kraken models: Z63/Z73/X53/X63/X73/X42/X52/X62/72 but any pump with the round locking ring will work.
Probably wouldn't be too hard to track down some GTX970 full coverage water blocks on the used market either.
Simplest mod...