M1 Mac RAM and storage can be upgraded after purchase, but it's not easy - 9to5Mac
Mac 101: How to Upgrade a Computer with Soldered Components
How to upgrade the RAM on your 13-inch MacBook Pro
MacBook Touchbar RAM Upgrade (13" Year 2016-2019) - YouTube
MacBook Touchbar RAM Upgrade (13" Year 2016-2019) - YouTube
192GB Memory Upgrade for 2019 Apple Mac Pro (6 x 32GB)
How to Upgrade RAM on a 2019 MacBook Pro
MacBook Pro (16-inch, 2019) review: Escaping the butterfly effect - CNET
2021 MacBook Pro Teardown: A Glimpse at a Better Timeline | iFixit News
v-Color DDR4 32GB (2 x 16GB) Hynix IC 2933MHz(PC3-23400) R-DIMM for Apple Mac Pro 2019 ECC Registered DIMM Dual Rank 2Rx8 1.2V CL21 Server Memory Ram Module Upgrade (VHA21ASDR8G8T-AG29RD) at Amazon.com