No, it means the output drive strength can be varied in 7 steps. Nothing to do with pull-ups or pull-downs, everything to do with EMI generation.
Yes it's pull up resistors.
Those pull up resistors are located in the processor.
The manufacture document says that those resistors are in series, but that's not logical. They must be in parallel.
https://www.pjrc.com/teensy/IMXRT1060RM_rev3.pdf
IMXRT1060RM_rev3.pdf
5–3
DSE
Drive Strength Field
Select one out of next values for pad: POR_B
000 DSE_0 — HI-Z
001 DSE_1 — Dual/Single voltage: 262/260 Ohm @ 1.8V, 247/157 Ohm @ 3.3V
010 DSE_2 — Dual/Single voltage: 134/130 Ohm @ 1.8V, 126/78 Ohm @ 3.3V
011 DSE_3 — Dual/Single voltage: 88/88 Ohm @ 1.8V, 84/53 Ohm @ 3.3V
100 DSE_4 — Dual/Single voltage: 62/65 Ohm @ 1.8V, 57/39 Ohm @ 3.3V
101 DSE_5 — Dual/Single voltage: 51/52 Ohm @ 1.8V, 47/32 Ohm @ 3.3V
110 DSE_6 — Dual/Single voltage: 43/43 Ohm @ 1.8V, 40/26 Ohm @ 3.3V
111 DSE_7 — Dual/Single voltage: 37/37 Ohm @ 1.8V, 34/23 Ohm @ 3.3V
So contrary to instructions, it seems to be 3 resistors in parallel being turned on, or off. (inst says series)
1.8v
62 ohms, 134 ohms, 262 ohms
001 = 262 Ohm
010 = 134 Ohm
011 = 88 Ohm
100 = 62 Ohm
101 = 50 Ohm
110 = 42 Ohm
111 = 37 Ohm
3.3v
57 ohms, 126 ohms, 247 ohms
001 = 247 Ohm
010 = 126 Ohm
011 = 83 Ohm
100 = 57 Ohm
101 = 46 Ohm
110 = 39 Ohm
111 = 34 Ohm
Teensy 4.1 uses:
MIMXRT1062DVJ6B
chip
https://www.mouser.com/datasheet/2/302/IMXRT1060CEC-1396580.pdf
22 k ohms, 47 k ohms, 100 k ohms
001 = 100 K Ohm
010 = 47 K Ohm
011 = 32 K Ohm
100 = 22 K Ohm
101 = 18 K Ohm
110 = 15 K Ohm
111 = 13 K Ohm