This is what I normally export and upload

2048px longest side - Grain 15 in Lightroom - Images sharpened in Photoshop but no additional sharpening in Lightroom.

NOT RESIZED - Using Lightroom export sharpening for screen (with grain applied)

LR Export Sharpen Setting - Low Sharpen

LR Export Sharpen Setting - Standard Sharpen

LR Export Sharpen Setting - High Sharpen

Barely noticeable and lacking in fine control.

NOT RESIZED - Sharpening manually in Lightroom before exporting (with grain applied)

Sharpen 35 LR

Sharpen 50 LR

Sharpen 75 LR

Sharpen 100 LR

Again, barely noticeable even at extreme sharpening amounts. Needs to be resized prior to sharpening.

RESIZED - Sharpening manually in Lightroom before exporting (with grain applied)

Resized Sharp 25

Resized Sharp 50

Resized Sharp 75

Resized Sharp 100

Images resized to 2048px long edge, exported with grain applied. Reimported, sharpening added before exporting again.

RESIZED - Sharpening manually in Lightroom before exporting NO GRAIN

Resized - No Grain - No Sharp

No grain -Sharpen 25

No Grain - Sharpen 50

No Grain - Sharpen 75

No Grain - Sharpen 100

No Grain - Sharpen 125

No Grain - Sharpen 150

Images resized then exported. Images reimported then sharpened. No grain appleid at any stage.

RESIZED then exported - Sharpened then exported - Grain added then exported

Resized - No Sharpen - with Grain 15

Sharpen 25 - with Grain 15

Sharpen 50 - with Grain 15

Sharpen 75 - with Grain 15

Sharpen 100 - with Grain 15

Sharpen 125 - with Grain 15

Sharpen 150 - with Grain 15

Images imported, resized and then exported. Images imported sharpened and then exported. Imaged imported and grain added before final export.

FINAL TEST - To avoid exporting three times, these images were resized and exported, then grain and sharpen was added simultaneously and exported again.

Resized then grain and sharpen 25 added

Resized then grain and sharpen 50 added

Resized then grain and sharpen 75 added

Resized then grain and sharpen 100 added

Resized then grain and sharpen 125 added

Resized then grain and sharpen 150 added

Final Conclusion for me personally.

Cons: Adding grain and then sharpening creates odd artefacts.

Cons: No discernible degradation to import, resize, export, import, sharpen, export, import, add grain, export. But you’re saving a jpeg three times and its a multi step process.

Pros: Import and resize to 2048px long edge, then export. Re-import, add 15 grain and add 100 sharpen. Export again at 2048px long edge.