Following the First PS5 Custom Themes released comes how to enable the PlayStation 5 (PS5) Browser permanently with the PS5 Partition Mount (PS5PM) Method Payloads proceeding the PS5 System Mount ELF alongside some App0_Testkit / Sandbox_Testkit PS5 Dumps with more details outlined below. 
Permanently Enable PS5 Browser confirmed via @ifcompass (aka Ifaicompa on Twitter):
BD-JB PS5 Dumps via @zecoxao on Twitter, who notes "also you can't replace testkit modules from existing retail ones. the keys differ"
Download: app0_testkit (322.1 MB)
Unconfirmed PS5 Keys (not added to PS5DevWiki) via @zecoxao on Twitter, according to PliskinDev they're scattered unfortunately and eventually confirmed fake: Pastebin.com:
Finally, some related articles for those new in the PlayStation 5 Scene (sorted by date with the oldest first):
Re-Enable Testkit App for PS5 (Permanently)
Spoiler
PS5 RNPS ePKG by Sony Official Server
no use until it's decrypted. they're the official psn apps from sony, bundled in an immense disgusting javascript amalgamate
ioctl is verifyDecryptRnpsBundle: 0xc0105203

- Enable browser permanently (directed to leeful.github.io/ps5)
- Overwrite the file to system_ex/rnps/apps Mount R/W method view here: PS5 Partition Mount (PS5PM)
- Download: NPXS40169.zip (30 KB)

Download: app0_testkit (322.1 MB)
- app0_ps5_testkit_105.zip
- app0_ps5_testkit_110.zip
- app0_ps5_testkit_111.zip
- app0_ps5_testkit_112.zip
- app0_ps5_testkit_113.zip
- app0_ps5_testkit_114.zip
- app0_ps5_testkit_200.zip
- app0_ps5_testkit_220.zip
- app0_ps5_testkit_225.zip
- app0_ps5_testkit_226.zip
- app0_ps5_testkit_230.zip
- sandbox_ps5_testkit_105.zip
- sandbox_ps5_testkit_110.zip
- sandbox_ps5_testkit_111.zip
- sandbox_ps5_testkit_112.zip
- sandbox_ps5_testkit_113.zip
- sandbox_ps5_testkit_114.zip
- sandbox_ps5_testkit_200.zip
- sandbox_ps5_testkit_220.zip
- sandbox_ps5_testkit_225.zip
- sandbox_ps5_testkit_226.zip
- sandbox_ps5_testkit_230.zip

Code:
PK0=C1E20574525331AE3E9ABFDFE3E64EB3AA1FD0CD30E3C286CEB84C0C280574E6
PK1=B8F64A4C3DC41A01C039BD1EBCDA3F9E25461024C8817CA8A0281126521884D0
PK2=5B031A912D8C2C8BACD4A919274827EBF4F855041C6B911DEABD26FCC38B2D86
PK3=53C9558316D34E6036A372BDA0238B4AB2D1B3E22074065BDD22DBC8584AD4C7
PK4=FBF4549BB1278E2336071887439BF819ACBB4292F7DA46729A76217419243C4B
PK5=89132F5E01643367499C866DB7B1E7C0C8040EF7DE13516BC7776D97FAB9DB7B
PK6=7FF33CBD9689177E5D8FD6BD2AA6BE0553893F63E525447DC5745BB9650CE69A
PK7=E4767D540A9E9531BDD3FB2302806A953E6920B15B8AE41C4D471B91422510A8
PK9=A5F56F9B07BD524BE2BFFD2C9AA3D80D070A5A5010BEF863F6C64BFA282B76F9
PK10=0DC5A3E6CF63DD71744F1854A6CBF64C13CE4358AE3C2EBE959C8C3B3F6B79B2
PKA0=3F3B86299E4598147DD1A9A8D314081FE8EE67DDFBAE20
PKA1=2D85350A3BC10ED683101EBBCAC799A5D1B87F6C32A833
PKA2=45DE1F88B189E2D453FEAEA559F02157A21F3DB92C7826
PKA3=B7C26B663BDDE355D1B516B7CE9F0D41A82A61FDC7A6B6
PKA4=6CB6896E6D2C61B33817C2927B032EC7FBE01D0B8BC75E
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- PS5 Debug Settings of DFI-T1000AA Test Kit
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- PS5 DevKit / TestKit Console Manager App
- PS5 Directory Tree Listing & Dumping Filesystem Script
- Astro's Playroom (HDD PS5 ASTROBOOT) File Dump
- PS5 File Dumping Utility and Pre-Compiled Images
- Guide on Dumping PS5 PSN Games the Proper Way
- PS5 System Partition Read / Write (R/W) Payload
- First PS5 Custom Themes with Background Music
- RNPS Custom Application.zip (4.4 MB) / 5.1 Firmware.zip (704.3 MB - includes app0.zip and sandbox.zip, PS5 Sandbox 5.1 Firmware)
- 3.20 img Factory manufacturing Model.zip (1.0 GB - includes first_img_writer.elf and rnps.img, PS5 3.20 IMG Factory Manufacturing Model)
Re-Enable Testkit App for PS5 (Permanently)
Spoiler

no use until it's decrypted. they're the official psn apps from sony, bundled in an immense disgusting javascript amalgamate
- 450.rar (178.2 MB - 4.50 rnps)
- app0_700_beta3.7z (32.68 MB)
ioctl is verifyDecryptRnpsBundle: 0xc0105203