You can get microSD to CF adapters, some even take 2-4 cards. The size at this point is easily 1-2tb affordably. Sadly they changed the interface with CF-2, so size is kinda limited if you wish to stay with strict CF, highest I have seen is 256gb.
Personally I have a bunch of microSD cards so i would just grab this adapter ...
https://www.amazon.com/QUMOX-COMPACT-MEMORY-READER-ADAPTER/dp/B019RD86NI and throw in 2 128gb cards. A true CF will give you better raw performance numbers wise, But with it being an old VIA thin client, even microSD is going to be faster then whatever was in there stock. Samsung EVO Class 10+ are pretty inexpensive, 2 128s and the adapter be under 50 usd.
Samsung 128gb for 15.99 lol
If 128 total be enough, even cheaper... at 10.49 each, still think 128s are the sweet spot price wise.
I believe these CompactFlash adapters interleave, not sure, could just be a JBOD. I would suggest using 2 of the same card, or just 1. Personally I would use 2.
There are dual microSD to MemoryStick Pro Duo adapters or w/e format the PSP used, Have one in my old PSP wherever it is. And I have seen dual of that to CF adapters. Just another idea be an Ipod adapter. Those use CF microdrives , but with the ribbon cable.
https://www.iflash.xyz/store/iflash-quad/
An adapter like that with the ribbon to CF adapter would work as well, and give you 4 card slots.
All depends how nutty you wanna get, or your budget. =)
On a side note, makes me want to start a project now. A passive laptop 2.5 IDE to CompactFlash adapter. I have never seen one. Could be interresting with an 2.5 IDE to SATA adapter, for use of SATA SSDs. Given you have to power it another way. Just curious if it would work. I'm strange like that. Sorry for all the edits, using my phone.