The recommendation is to not do that anymore. As of SQL 2016 (or perhaps as early as 2012) the setup is going to default to the recommended and builtin accounts for all its services. You shouldn't really be creating dedicated accounts anymore as you shouldn't need them. There are a few exceptions for advanced scenarios like failover clusters from my understanding. So my naming recommendation is "don't".
In previous companies that either had old SQL servers that pre-date this or were stuck in their SOP-style world of mandating accounts then they would put "service" in the name somewhere but often shortened it to something like sql-svc-dev
or something. The problem is, of course, that if you have more than 1 SQL server instance then you should really be creating separate accounts for each one as you don't want to accidentally give 1 service account access to another server's stuff. That means you run into the questionable naming convention of sql-svc-myserverinstance-dev
or something like that. Using the recommended accounts resolves these issues.