Is the performance of the JVM/PostgreSQL/NGINX on OpenBSD the same as on Linux? Are there any reliable OpenBSD VPS providers?
Reliable and cheap, even more so if you take 10 minutes to google for a discount coupon.
Operating systems get deployed from an image, and typically expand the own partitions to fill up the disk... OpenBSD can't do this, which makes things pretty tricky.
As for VPS providers, I've heard good things about 1984[0], though I haven't used them myself (yet; I'll probably do this pretty soon). I've also used EDIS[1] without any particular problems. Both provide OpenBSD as OS options.
[0]: https://www.1984.is/ (in Icelandic, but there's a drop-down to set the language to English). [1]: http://www.edis.at/en/home/