@ hammeredalways, i'm glad that you brought the issue of the "Gwardia Piesza Koronna", which I believe look absolutely stunning and fit into the timeperiod perfectly. Arguabley they could be a replacement of the current grenadiers seeing as the current polish grenadiers have similar uniforms, simply their hats are different, and i'd argue that the "Royal Foot Guard" (translation) is much more fitting with their hat and should replace the current Polish Grenadier head gear.
Yet as is obviously known, the Poles lack any reflection of their diverse infantry, which could be argued was better organized and more efficient than their famed calvalry in the late 18th century.
For instance, as ilustrated in the following image, we have eight different various types of infantry, all of them supported by an illustration and an explanation.
POLISH ARMY IN 1794
1, 2 and 7- Infantry from the Wodzicki Regiment
1- Adorned in a Dark Blue Uniform with Red Stripe down Pants and Red Inner Jacket. Dark Blue Hat with Silver Plate and White Trim on top. Criss crossing straps across chest (White)
2- Adorned in a Dark Blue Uniform with Yellow Stripe down pants and Yellow Inner Jacket. Dark Blue Hat with White Cross and White Trip On top. Criss crossing straps across chest (white)
7- Adorned in a Dark Blue Uniform with Red Stripe down Pants and Red Inner Jacket. Dark Blue Hat with Silver Plate and White Trim on top. Criss crossing straps across chest (White)
3- Infantry from the Dzialynski Regiment
3- Adorned in a Dark Blue Uniform with white pants and Red Inner Jacket. Dark Blue Grenadier Hat with Gold Plate covering ENTIRE front. One White Strap
6- Sharpshooters/Light Infantry from the Dembowski Regiment
6- Green Uniforms
8- Sierakowski's Fusiliers
8-Light Blue Uniforms
MORE WODZICKI REGIMENT IMAGES
Polish Army in 1791
1. Oficer regimentu 10 pieszego koronnego szefostwa Działyńskiego w mundurze wielkim wg przepisu Komisji Wojskowej O.N z lipca 1789
Polish Officer from 1789
2. Żołnierz kompanii strze3leckiej regimentu 10 pieszego koronnego w mundurze wielkim z lat 1791-1792
Polish Soldier from the 10th foot Sharpshooter Regiment
3. Gemain (szeregowy) regimentu 10 pieszego koronnego w mundurze wielkim z lat 1791-1792
Line Infantry from the 10th foot Guard Regiment
12 i 13 Regiment Koronny - 12th (white) and 13th (blue) Crown Infantry Regiment
Regiment Królewicza - Crown Prince's Own
Regiment Królowej - Queen's Own Regiment
Pułk Czartoryskiego - Czartoryski's Cossack Regiment
Straż Przednia Litewska - Lithuanian Front Guard