Funny, I have released a similar article lately, but with a different goal:
This is a full text search, however, the caveat is to use a database with a small rest-like script.
The sql file for the database is generated when Hugo runs and the Javascript does the search.
The downside of your solution is of course that it is keyword only and that the download size grows as your blog grows and the search will become slower over time, especially with limited data rates in non western countries.
But, as we Germans say, you got to die one death.