Single = True = One Piece = Full monocoque carbon frame.
Full monocoque frame means no junction point between rear and front triangle.
It is different from Semi = Half = Double Mold monocoque frame. However, many brands tend to do word play such as Orbea(Who said they are monocoque/actually half monocoque)

Those frames are TCM Frame:
Titici Alfa
Titici REVO
Bit Brixia
Parlee Ouray
Parlee Taos
Bottecchia EMME 4 SLI
Bmc Roadmachine Mpc
Bmc Timemachine Mpc
Cipollini Dolomia
Cipollini The One
Cipollini NK1K
Cipollini AD.ONE
Elves Vanyar Rim
Elves Vanyar Disc
SEKA SPEAR
Winspace C5
Winspace SLC 3.0
Workswell wcb-r-093 = Schmolke KOM
Quick Pro AR:One
Quick Pro SR:One = Flybike FM906-D
Quick Blade
Quick One Piece = Flybike FM906
Quick Zeit Pro = Flybike FM1056 = Carbonda 1056
Quick Rime = Holdsworth Corsa
Planet X XLS EVO = Donnely C//C = BOMBTRACK TENSION C = Guerciotti Eureka CX = S1NEO CX2022 = GHISAILLO GX-110 = Flybike FM686 = Forwards CX
Quick HARE = Carbonda 707 = Flybike FM1186 = Forwards Gravel Race = Detrail Grus
Swi Thrama
Ribble Ultra
Ribble Endurance SL/R
Lykos ACT01
Giant MCR
CADEX Tri
Fuji Jari Carbon(Before 2022)
Fuji Jari Carbon CX
Somec MULTISTRADE K
Ritte ACE-Carbon
BLB-London Aeon
Rodeo Traildonkey 4.0
Eddy Merckx MXM
Vitus ZX-1 EVO
Vitus Vitesse EVO

WILIER Jena (Not sure)
Ibis Hakka MX (Not sure)
Enve Melee (Not sure)
Kinesis Crosslight CSIX2 (Not sure)
Ribble Gravel SL (Not sure)

No More update on MTB FRAME
XDS TXC1
MCELO EVO
Stevens Sonora
UNNO XC
......

This is just a list to let you know which is single-piece monocoque structure frame.