I think you both have merit, the RAM is going to be easier upgrade compared to an NVME drive.
However DDR4 is basically at end of life and the cheapest it is going to be, as DDR5 will start to become more main stream.
Getting 16GB now and say upgrading another 16GB in say a years time could be costly as DDR4 supply starts to drop/no longer in stock.
Right now OP has 32GB of DDR4 ram 3600 clocked for approx $220.00.
My suggestion would be get this slightly lower clocked ram 32GB of DDR4 ram 3200 for $159 and put the extra money towards a better boot drive.
P.S i don't know what makes a better boot drive but i personally don't think DDR4 clock speed 3200 vs 3600 is worth the extra $60.
Admittedly i could be way wrong like my BIOS comment.... think this is my 6cents so far



