I only just installed Signal in some abandoned corner of one of my devices to be able to communicate with my 'highschool' classmates (in reality a Dutch Gymnasium so a totally different school system and age group but you get the idea) and had to get the blasted thing working without Google services on a device which for some specific purposes sometimes enables these but mostly has them disabled. As soon as Signal gets a whiff of even a stub of Google services is refuses to work without a fully fledged Google services implementation. To fix this I had to add 'disable Signal' to my 'enable rudimentary Google services' script and to do that I had to find the package name:

   org.thoughtcrime.securesms

So yes, they're still called 'secure SMS' even though that is no longer part of the deal.

I'll only use it for the specified purpose since I far prefer my own XMPP server with OMEMO encryption - which is based on the same 'double ratchet' keying as Signal uses.