Perhaps we'll give HikariCP a chance. However, please keep in mind that the goal of the YDB team is to enhance database performance. We needed virtual threads to make TPC-C efficient enough to generate a reasonable load on a modest amount of hardware.
Virtual threads aren't necessarily faster, you still have just as many sockets and network connections as before. You can easily spawn 5000 platform threads, and if that's not enough, there are quite a few user-space implementations of fibers/coroutines/async etc on the JVM that can deal with many outlying requests (Cats/ZIO in Scala, Kotlin coroutines, the Play framework, concurrent.Future, etc.)