One small image, no end in sight.

A tileable (seamless) texture repeats without a visible edge. Use one in Blender with Repeat and the Mapping node, lay out UVs for it, make one from a photo in a Photoshop-style workspace with Offset, the Clone Stamp and the Healing Brush, keep every PBR map tiling, project it without UVs and hide the repetition.

STAGE

SAME KEYS AS THE REAL TOOLS

Shortcuts you can use here

Keys work while the mouse is over the workspace. In the Photoshop stages they follow Photoshop; in the Blender stages, Blender.

C · S · J · H: Photoshop: Crop, Clone Stamp, Healing Brush, Hand
Alt + click: Photoshop: set the source of the Clone Stamp or the Healing Brush
[ · ]: Photoshop: smaller · bigger brush
CtrlJ · CtrlI · ShiftCtrlU: Photoshop: Duplicate Layer · Invert · Desaturate
Space + drag · Ctrl0: Photoshop: pan · Fit on Screen (the wheel zooms)
G · S · R · X Y: Blender UV Editor: move, scale, rotate islands, lock to U or V; type a number and Enter
A · AltA: Blender: select all · none
CtrlZ · Home: Undo (both) · frame the view

BACK IN THE REAL TOOLS

Tileable textures in Photoshop and Blender

The same steps as in this lab. Photoshop menus change little between versions; the Blender names are the ones in the Shader Editor and the UV Editor.

Photoshop: crop a square (Crop Tool, 1:1 (Square)), then Image › Image Size to a power of two. Even out the light before anything else (a blurred, desaturated, inverted copy in Linear Light at 50 %, or a High Pass).
Filter › Other › Offset with half the width and height and Wrap Around, then Clone Stamp (S) and Healing Brush (J) over the cross. Edit › Content-Aware Fill can help on big areas. Check with View › Pattern Preview.
Make Roughness, Normal and Height from the finished tileable colour, or repeat every offset and every retouch on each map. Tools that make maps (Substance 3D Sampler, Materialize…) have a tiling option: keep it on.
Blender: Image Texture node with Extension › Repeat; a Mapping node (CtrlT with Node Wrangler) sets the size. Or scale the UV islands: with a tileable texture they may go outside 0–1 and overlap.
Same metres per tile on every island, no stretching, rows along U. Unwrap walls that meet as one strip so the pattern turns the corner.
No good UVs: Texture Coordinate › Object + Projection › Box with some Blend. To hide the repeat, multiply a large Noise Texture over the colour and mix a second texture with a size that is not a multiple of the first.