So I'd like to have one custom rest handler that allows for URLs like
restmap.conf
[script:myapp_files]
match=/myapp/files*
python.version=python3
handler=myapp_files.req
methods=GET,POST,PUT,DELETE
script = myapp_files.py
scripttype = persist
[expose:myapp_files]
pattern=myapp/files*
methods=GET,POST,PUT,DELETE
I would presume that if the docs don't say a regex is allowed then a regex is not allowed.
There are examples, however, of pattern use in the OOTB restmap.conf files. See splunk_instrumentation/default/restmap.conf for an example. In your case adding a slash may help.
match=/myapp/files/*
If it works then submit feedback on that documentation page to ask them to say patterns are allowed.