According to MDN, the list attribute can be used for <input> elements of type color to provide a list of predefined colors. That page also indicates that
antplus
window-decoration
ibm-cloud-infrastructure
idle-timer
moveable
oc4j
ado.net-entity-data-model
sametime
nps
opendkim
asgi
angular-material-9
actor-model
urdu
usbserial
string-metric
metafor
spring-data-couchbase
git-diff
ofstream
cycle-sort
azure-sentinel
mahout
spell-checking
nand2tetris
sodium
xcsettings
http-redirect
bytestring
lua-table