The BV_BV9500Pro_V1.0_20180829 firmware worked for getting my phone to a state where I could work on modding, so this confirms both links for the BV9500 Pro work.
Though I've not tested the 2018092919_s32v63c2k_jk_pro zip with my phone.
Whereas now I know the BV_BV9500Pro_V1.0_20180829 firmware (29th aug 2018 firmware) didn't work on someone else's BV9500, I speculate different hardware revisions of the "PRO" hardware?
GPD-WIN - Pocket PC (Modded for Data SIM)
BlackView BV9500 - Pocket PC & phone replacement (Currently debugging the kernel)
Librem 5 or faster alternative.