So I had forgotten… PicoMite actually includes a font that’s this size.
It’s font #8 which is 4x6 (actually 3x5 characters with the one pizel gap on side and bottom).
I only realized that after I made this Pico-8 font. Unless I messed up, it should be a pixel perfect version of the Pico-8 font (both upper and lower case). So either this one or the official font #8 could be used for a 80 column wide font. Might have to break out a magnifying glass to read it on the PicoCalc though!
' pico8.bas
' Font type : Full (96 characters)
' Font size : 4x6 pixels
' Memory usage : 292 bytes
' Font adapted from: https://www.lexaloffle.com/bbs/?tid=3760
DefineFont #10
60200604 44000000 00AA4040 A0AEAE00 A2406EEC EACCA048 000048E0 42408848
E4A44022 00E404A0 00800400 000000E0 80442440 C4E0AAEA E8E2E044 E062E2E0
E820E2AA EAE8E0E2 2022E2E0 EAE0EAEA 040420E2 80040400 0E208424 2484000E
4060E280 4A60A84A CAEAA0EA 608868E0 E8E0AACA C8E8E0C8 E08A6880 E4A0EAAA
44E4E044 A0CAAAC0 EEE08888 AACAA0AA C0AA6AA0 4A80E8EA CAEA60AC C0E268A0
AA4044E4 AEAA60AA E0AEAA40 AAA04AAA 48E2E0E2 C088C8E0 62204484 004A6022
E0000000 0E000042 CA0CA0AE E0880EE0 0EC0AA0C C80EE0C8 E08A0E80 0EA0AE0A
440EE044 A0CA0AC0 0EE08808 AA0CA0EA C0AA06A0 0480AE0E AC0E60AC C08206A0
0A40440E AE0A60AA E0AE0A40 0AA04A0A 280EE0E2 60C464E0 C4404444 802EC064
E0AA0400
End DefineFont
print "pico8"
font 10, 1
for i = 32 to 127
if i mod 16 = 0 then print
print chr$(i);
next i
print
Just for completeness, here’s the .c definition of the same thing (like the fonts compiled into PicoMite):
// pico8.c
// Font type : Full (96 characters)
// Font size : 4x6 pixels
// Memory usage : 292 bytes
// Font adapted from: https://www.lexaloffle.com/bbs/?tid=3760
fontdatatype pico8[292] PROGMEM={
0x04,0x06,0x20,0x60,
0x00,0x00,0x00, // Chr$(32)
0x44,0x40,0x40, // Chr$(33) !
0xAA,0x00,0x00, // Chr$(34) "
0xAE,0xAE,0xA0, // Chr$(35) #
0xEC,0x6E,0x40, // Chr$(36) $
0xA2,0x48,0xA0, // Chr$(37) %
0xCC,0xEA,0xE0, // Chr$(38) &
0x48,0x00,0x00, // Chr$(39) '
0x48,0x88,0x40, // Chr$(40) (
0x42,0x22,0x40, // Chr$(41) )
0xA4,0xE4,0xA0, // Chr$(42) *
0x04,0xE4,0x00, // Chr$(43) +
0x00,0x04,0x80, // Chr$(44) ,
0x00,0xE0,0x00, // Chr$(45) -
0x00,0x00,0x40, // Chr$(46) .
0x24,0x44,0x80, // Chr$(47) /
0xEA,0xAA,0xE0, // Chr$(48) 0
0xC4,0x44,0xE0, // Chr$(49) 1
0xE2,0xE8,0xE0, // Chr$(50) 2
0xE2,0x62,0xE0, // Chr$(51) 3
0xAA,0xE2,0x20, // Chr$(52) 4
0xE8,0xE2,0xE0, // Chr$(53) 5
0xE8,0xEA,0xE0, // Chr$(54) 6
0xE2,0x22,0x20, // Chr$(55) 7
0xEA,0xEA,0xE0, // Chr$(56) 8
0xEA,0xE2,0x20, // Chr$(57) 9
0x04,0x04,0x00, // Chr$(58) :
0x04,0x04,0x80, // Chr$(59) ;
0x24,0x84,0x20, // Chr$(60) <
0x0E,0x0E,0x00, // Chr$(61) =
0x84,0x24,0x80, // Chr$(62) >
0xE2,0x60,0x40, // Chr$(63) ?
0x4A,0xA8,0x60, // Chr$(64) @
0x4A,0xEA,0xA0, // Chr$(65) A
0xEA,0xCA,0xE0, // Chr$(66) B
0x68,0x88,0x60, // Chr$(67) C
0xCA,0xAA,0xE0, // Chr$(68) D
0xE8,0xC8,0xE0, // Chr$(69) E
0xE8,0xC8,0x80, // Chr$(70) F
0x68,0x8A,0xE0, // Chr$(71) G
0xAA,0xEA,0xA0, // Chr$(72) H
0xE4,0x44,0xE0, // Chr$(73) I
0xE4,0x44,0xC0, // Chr$(74) J
0xAA,0xCA,0xA0, // Chr$(75) K
0x88,0x88,0xE0, // Chr$(76) L
0xEE,0xAA,0xA0, // Chr$(77) M
0xCA,0xAA,0xA0, // Chr$(78) N
0x6A,0xAA,0xC0, // Chr$(79) O
0xEA,0xE8,0x80, // Chr$(80) P
0x4A,0xAC,0x60, // Chr$(81) Q
0xEA,0xCA,0xA0, // Chr$(82) R
0x68,0xE2,0xC0, // Chr$(83) S
0xE4,0x44,0x40, // Chr$(84) T
0xAA,0xAA,0x60, // Chr$(85) U
0xAA,0xAE,0x40, // Chr$(86) V
0xAA,0xAE,0xE0, // Chr$(87) W
0xAA,0x4A,0xA0, // Chr$(88) X
0xAA,0xE2,0xE0, // Chr$(89) Y
0xE2,0x48,0xE0, // Chr$(90) Z
0xC8,0x88,0xC0, // Chr$(91) [
0x84,0x44,0x20, // Chr$(92) backslash
0x62,0x22,0x60, // Chr$(93) ]
0x4A,0x00,0x00, // Chr$(94) ^
0x00,0x00,0xE0, // Chr$(95) _
0x42,0x00,0x00, // Chr$(96) `
0x0E,0xAE,0xA0, // Chr$(97) a
0x0C,0xCA,0xE0, // Chr$(98) b
0x0E,0x88,0xE0, // Chr$(99) c
0x0C,0xAA,0xC0, // Chr$(100) d
0x0E,0xC8,0xE0, // Chr$(101) e
0x0E,0xC8,0x80, // Chr$(102) f
0x0E,0x8A,0xE0, // Chr$(103) g
0x0A,0xAE,0xA0, // Chr$(104) h
0x0E,0x44,0xE0, // Chr$(105) i
0x0E,0x44,0xC0, // Chr$(106) j
0x0A,0xCA,0xA0, // Chr$(107) k
0x08,0x88,0xE0, // Chr$(108) l
0x0E,0xEA,0xA0, // Chr$(109) m
0x0C,0xAA,0xA0, // Chr$(110) n
0x06,0xAA,0xC0, // Chr$(111) o
0x0E,0xAE,0x80, // Chr$(112) p
0x04,0xAC,0x60, // Chr$(113) q
0x0E,0xAC,0xA0, // Chr$(114) r
0x06,0x82,0xC0, // Chr$(115) s
0x0E,0x44,0x40, // Chr$(116) t
0x0A,0xAA,0x60, // Chr$(117) u
0x0A,0xAE,0x40, // Chr$(118) v
0x0A,0xAE,0xE0, // Chr$(119) w
0x0A,0x4A,0xA0, // Chr$(120) x
0x0A,0xE2,0xE0, // Chr$(121) y
0x0E,0x28,0xE0, // Chr$(122) z
0x64,0xC4,0x60, // Chr$(123) {
0x44,0x44,0x40, // Chr$(124) |
0xC4,0x64,0xC0, // Chr$(125) }
0x2E,0x80,0x00, // Chr$(126) ~
0x04,0xAA,0xE0, // Chr$(127)
};
It works on the old MMBasic for Windows port as well, which I used to get this screenshot, since it’s a bit of a pain to get one easily from the PicoCalc, and I couldn’t be bothered copying the file back from it. 
