With zero modular components, there's no chance of upgrading any of this hardware. Speak now or forever hold your chips:

9th-generation Intel Core i7-9750H 6-core processor

16x SK Hynix H5AN8G8NAFR 8 Gb DDR4 SDRAM (16 GB total)

AMD Radeon Pro 555X GPU

4x Micron MT51J256M32HF-70:B 8 Gb GDDR5 RAM (4 GB total)

Apple T2 APL1027 339S00533 coprocessor, layered over 1 GB Micron D9VLN LPDDR4 memory

Toshiba TSB3226AW8815TWNA1 and TSB3226XZ2939TWNA1 flash storage (256 GB total)

Intel JHL7540 Thunderbolt 3 controller