May I ask, what pull-up? And how do you power up your board? Fast turn-on from a truck battery via strobed switcher? (Is it this application you once told about? LED display in a bus?)
you may: bus battery 24V (see note1) - PowerTrends switcher 5v - LDO 3v3. Separate power (150W) for the LEDs. The reset pin is pulled to Vdd by 2k2. When I have multiple uCs on the same board, I always use an external supervisor for the reset, the likelihood that the processors come out of reset in any particular sequence is ZERO, just look at the tolerances of the reset pulse duration. for single processor boards with SILabs chips I have had no problems using the internal "supply monitor" with a pullup.

There may be issues with slowly rising Vdd, but NOT regarding the "supply monitor" forcing resets during power up/power down/brownouts.

I repeat a previous statement of 'impression': "chips with enough analog features to make part of the die analog have good "supply monitors", purely digital ones tend to have lousy ones".

Erik

Note1) on the desk this is a boxed net powered 200W 24V supply, still no problems.