Inspiron 3793 Upgrades?

RAM:  2 slots, 16 G each.

Storage:  one 2.5" SATA, one M.2 SATA or NVMe.

Service and specifications manuals:

https://www.dell.com/support/home/en-us/product-support/product/inspiron-17-3793-laptop/docs

Nothing else is upgradeable (CPU, GPU, etc.).

Can I also use ONE 32 GB modul + ONE 8 GB modul or only symmetric ?
2 x 16 GB e. g.?

Officially, 32G modules are not supported.  That doesn't mean the configuration won't work, but bear in mind that 8+32 means only half the RAM will run in dual channel mode -- the other 16 will be slower single channel.

I'm looking to do this too. Am I right in thinking I'll get significant improvements if I upgrade the following:

1. The 8GB DDR4 (2666 MHz) to 
   16GB DDR4-3200 SODIMM
   
   
2. The 128 GB SSD (BC501A NVMe SK hynix, drive C) to 
   Crucial T500 500GB PCIe Gen4 NVMe M.2 SSD with Reads/writes up to 7,200/5,700MB/s
   
   
3. The 1TB Seagate ST1000LM035 2.5-Inch 5.4K SATA HDD to 
   Crucial BX500 SATA SSD 2TB, 2.5" Internal SSD