RPI Zero W két SSID boot választ

Igen, jónak tűnik.

Ha nem adod meg a priority paramétert, akkor minden bejegyzés 0-s prioritású (ez a leggyengébb), és pont az történik, mint amit akarsz. Kivéve, a megadott scan_ssid=1, illetve a scan_ap=2 esetén, ekkor a fájlbeli sorrend dönt.

# priority: priority group (integer)
# By default, all networks will get same priority group (0). If some of the
# networks are more desirable, this field can be used to change the order in
# which wpa_supplicant goes through the networks when selecting a BSS. The
# priority groups will be iterated in decreasing priority (i.e., the larger the
# priority value, the sooner the network is matched against the scan results).
# Within each priority group, networks will be selected based on security
# policy, signal strength, etc.
# Please note that AP scanning with scan_ssid=1 and ap_scan=2 mode are not
# using this priority to select the order for scanning. Instead, they try the
# networks in the order that used in the configuration file.

# AP scanning/selection
# By default, wpa_supplicant requests driver to perform AP scanning and then
# uses the scan results to select a suitable AP. Another alternative is to
# allow the driver to take care of AP scanning and selection and use
# wpa_supplicant just to process EAPOL frames based on IEEE 802.11 association
# information from the driver.
# 1: wpa_supplicant initiates scanning and AP selection; if no APs matching to
#    the currently enabled networks are found, a new network (IBSS or AP mode
#    operation) may be initialized (if configured) (default)
# 0: This mode must only be used when using wired Ethernet drivers
#    (including MACsec).
# 2: like 0, but associate with APs using security policy and SSID (but not
#    BSSID); this can be used, e.g., with ndiswrapper and NDIS drivers to
#    enable operation with hidden SSIDs and optimized roaming; in this mode,
#    the network blocks in the configuration file are tried one by one until
#    the driver reports successful association; each network block should have
#    explicit security policy (i.e., only one option in the lists) for
#    key_mgmt, pairwise, group, proto variables
# Note: ap_scan=0/2 should not be used with the nl80211 driver interface (the
# current Linux interface). ap_scan=1 is the only option working with nl80211.
# For finding networks using hidden SSID, scan_ssid=1 in the network block can
# be used with nl80211.
# When using IBSS or AP mode, ap_scan=2 mode can force the new network to be
# created immediately regardless of scan results. ap_scan=1 mode will first try
# to scan for existing networks and only if no matches with the enabled
# networks are found, a new IBSS or AP mode network is created.

# scan_ssid:
#	0 = do not scan this SSID with specific Probe Request frames (default)
#	1 = scan with SSID-specific Probe Request frames (this can be used to
#	    find APs that do not accept broadcast SSID or use multiple SSIDs;
#	    this will add latency to scanning, so enable this only when needed)