The Raspberry Pi fits the bill better - it will run some form of desktop Linux for a long time into the future and it is such a simple cheap design - just 4 IC's with some bits.
The same can't be said of the A1200 - flaky old circuitry that you cannot source new parts for except cannibalize donor boards - and it is huge and slowww.
The pi is largely undocumented and otherwise proprietary. It's owned by broadcom who are otherwise known for putting everything behind an nda. No, the pi is a lot, but it's not a platform i would bet on to be available in 50 years.
Yes the Amiga OCS can be implemented on a FPGA but nobody is running the 68K architecture (Paula/Agnus/Denise ain't nothing special) anymore except for ColdFire variants still used in the automotive world and in laser printers.
ARM is rather ubiquitous at this stage considering the number of implementations in the world since the first Android phones went on sale.
The same can't be said of the A1200 - flaky old circuitry that you cannot source new parts for except cannibalize donor boards - and it is huge and slowww.