Make sure you have git, go and gmake installed on your system.
$ doas pkg_add -v git go gmake
Make sure your gopath is set:
$ export GOPATH=~/go
$ echo "$GOPATH"
$ export PATH="$PATH:$GOPATH/bin"
The install_unsupported target works nicely for openbsd. This will install
gx, gx-go and run go install -tags nofuse ./cmd/ipfs.
$ go get -v -u -d github.com/ipfs/go-ipfs
$ cd $GOPATH/src/github.com/ipfs/go-ipfs
$ gmake install_unsupported
if everything went well, your ipfs binary should be ready at $GOPATH/bin/ipfs.
$ ipfs version