Proceeding his recent PS4 Debug Trophies ShellCore Patch, PlayStation 4 developer @flatz (Twitter) made available both an (f)SELF loader via server fPKG application and a PS4 Stub Library Maker (using OrbisLibGen generate stub files) on Github alongside a Windows compiled PKG version below by @zecoxao on Twitter to try fSELFs without installing the full Package file saving scene devs time testing changes. 
Download: payload_ldr_with_POWER.pkg (7.88 MB - Compiled by notzecoxao) / payload_ldr_with_POWER_v2.pkg (7.88 MB - V2) / payload_ldr_v3.pkg (Payload LDR V3) / 505dev.tar.gz (587.59 KB) / 505dev.tar.gz (586.52 KB - Updated) / ps4-hen-vtx-master.tar.gz (80.78 KB - Adds Usermode Printf to Klog in HEN) / ps4_stub_lib_maker-master.zip / GIT / ps4_payload_ldr-master.zip / GIT
Also below is a brief demo video by Lil Xo of the PS4 Payload Loader launching before receiving a CE-34224-5 'Cannot start the application' error followed by a fixed version, and a screenshot of the ZLibTest.pkg being loaded ready to use.
From the README, to quote: ps4_stub_lib_maker
Stub library maker (with sample library)
Prerequisites:
And from the other README, to quote: ps4_payload_ldr
(f)SELF loader via server (fPKG application)
Prerequisites:
Small patch (5.01 offsets) to redirect userland printf into kernel's log (uart, etc) via Ybin.me:
Ops, forgot this:
This my patch also enable kprintf for mira logger 5.05FW >
And from zecoxao also comes a brief guide on testing your own PlayStation 4 homebrew, to quote:
Tools:
Step1: Create a folder called self inside data folder (You can use ftp or orbisman for this)
Step2: Launch HEN 1.8
Step3: If needed, launch mira aswell(for logging your homebrew/game while it's being tested)
Step4: Install payload_ldr pkg
Step5: Launch payload ldr (the screen should hang at start)
Step6: Send the main eboot (it MUST be a self file)
Other options are available but for now i'll only use this one
Step7: Your homebrew should now run and (if you have it) logs should be displayed on putty/some other Telnet/Serial logger
Cheers to @DEFAULTDNB and @Wultra for the PS4 scene news tips earlier today!
Download: payload_ldr_with_POWER.pkg (7.88 MB - Compiled by notzecoxao) / payload_ldr_with_POWER_v2.pkg (7.88 MB - V2) / payload_ldr_v3.pkg (Payload LDR V3) / 505dev.tar.gz (587.59 KB) / 505dev.tar.gz (586.52 KB - Updated) / ps4-hen-vtx-master.tar.gz (80.78 KB - Adds Usermode Printf to Klog in HEN) / ps4_stub_lib_maker-master.zip / GIT / ps4_payload_ldr-master.zip / GIT
Also below is a brief demo video by Lil Xo of the PS4 Payload Loader launching before receiving a CE-34224-5 'Cannot start the application' error followed by a fixed version, and a screenshot of the ZLibTest.pkg being loaded ready to use.

Stub library maker (with sample library)
Prerequisites:
- *** (oouch! need to move to open source *** in the future...)
- Linux & Wine (I'm building it on trueOS but it could be backported to Windows)

(f)SELF loader via server (fPKG application)
Prerequisites:
- Kernel payload changes & ShellCore patches: https://gist.github.com/flatz/f510bc6647a33cef1532c65c7881f32d
- *** (oouch! need to move to open source *** in the future...)
- Publishing tools with fPKG patches
- Linux & Wine (I'm building it on trueOS but it could be backported to Windows)
- Jailbreaking/rooting requires custom syscall which does that (see jailbreak.c).
Code:
1st 0x117E0
2nd 0x63E24D
3rd 0x0x319A53
Code:
DECLARE_FUNCTION(0xECB40, console_write, int, struct cdev* dev, struct uio* uio, int ioflag);
DECLARE_FUNCTION(0x49D640, deci_tty_write, int, struct cdev* dev, struct uio* uio, int ioflag);
DECLARE_FUNCTION(0x2A8010, cloneuio, struct uio*, struct uio* uiop);
DECLARE_VARIABLE(0x14B5E80, M_IOV, struct malloc_type*);
static int deci_tty_write__hook(struct cdev* dev, struct uio* uio, int ioflag) {
struct uio* cloned_uio = NULL;
int ret;
cloned_uio = cloneuio(uio);
ret = deci_tty_write(dev, uio, ioflag);
if (cloned_uio) {
if (*console_cdev)
console_write(*console_cdev, cloned_uio, ioflag);
free(cloned_uio, M_IOV);
}
return ret;
}
*(uint64_t*)(kernel_base + 0x19FC168) = (uint64_t)&deci_tty_write__hook;
Code:
DECLARE_VARIABLE(0x1AC5158, console_cdev, struct cdev**);
Code:
kmem = (uint8_t *)&gKernelBase[0x00436136];
kmem[0] = 0xEB;
kmem[1] = 0x1E;
Tools:
- HEN 1.8: ps4-hen-vtx.bin
- PS4Jailbreak 5.05 (HEN): index.html
- payload_ldr: payload_ldr_verbose.pkg
- FTP payload/OrbisMAN
- (Optional But Recommended) Mira for usermode logs / UART
Step1: Create a folder called self inside data folder (You can use ftp or orbisman for this)
Step2: Launch HEN 1.8
Step3: If needed, launch mira aswell(for logging your homebrew/game while it's being tested)
Step4: Install payload_ldr pkg
Step5: Launch payload ldr (the screen should hang at start)
Step6: Send the main eboot (it MUST be a self file)
Code:
sender.py --endpoint 192.168.1.4 eboot.bin
Step7: Your homebrew should now run and (if you have it) logs should be displayed on putty/some other Telnet/Serial logger
Cheers to @DEFAULTDNB and @Wultra for the PS4 scene news tips earlier today!