I have always used a realistic but totally fake name with Amazon (and other country specific tld) and any other online merchants. However, I always use my full name on my credit card (or family member credit card if I purchase on their behalf). Moreover, for delivery I use another real name (only her first name) to be sure they deliver to the right person who is always available.
This is probably a new security thing for new accounts, my Amazon accounts are from 2009~2011 and I regularly use them (daily even).
This is so that if there is a breach/hack at the merchants system my own exposure is as limited as possible or as messy as possible (i have multiple different addresses and multiple different names in each account, some not valid anymore because someone or I moved or changed cards).
Unfortunately, due to the constant willful or untested shenanigans of various website I have set up all my system’s Firefox profiles to spoof by default its user agent (and other JavaScript properties) as Windows 11, x86_64, Firefox LTS (even if I use latest, Aurora or beta). Some blantant recent example: YouTube uses lower quality options on browsers running on Arm-based systems — misreporting as an x86 CPU appears to be a widespread browser fix
Doing so has helped me and many friends/family I switched to a flavor of Linux (mostly Mint, but sometimes LMDE or Ubuntu or specific requirements/demands) avoid numerous dumb problems.
Even on mobile sometimes UX breaking issues creep up.