Depending on the use and location, this would be illegal without a broadcasting license in most parts of Canada. Low power FM broadcasting is allowed in remote areas. Can't find the detailed information right now but the allowed FM power and range for personal use in urban areas is only good for a few feet. The most common use for personal FM transmitters is in devices that have very low power integrated FM transmitters. These are typically much less than 500mW and can be found in devices such as music players that are made for use with FM car radios.
What is the intended use? There may be other alternatives.
I intend on broadcasting Sunday church masses to our (small, but not that remote) town.
My area mostly comprises of elderly people who don't own or have access to the Internet or don't know how to use it, so an Internet broadcast is out of the question for that reason. That's why I think FM is the best option for my area.
You might be able to get a low power permit for that purpose. 500mW (0.5W) might not be enough power. From what I read, a low power permit allows up to 5W. With a decent antenna that could travel several miles. Not sure what the requirements and cost of obtaining the permit would be but it's much simpler than a regular station license. I would contact the CRTC.
Max power is usually stipulated as Effective Radiated Power (ERP), Relative to a Dipole....which is Max allowed to be emitted by the Antenna.
If using [the popular] Vertical Dipole [TRUE OMNI], Max Antenna Gain is 0 dBd (= 2.15 dBi), so ERP is same as Transmitter Output (less hopefully small Coax Loss).
OTOH, if you chose to use some Other, Higher Gain Antenna, such as for example a "typical" FM Turnstile Antenna, Max Antenna Gain could be HIGHER , since most are Bi-Directional and NOT OMNI, so must use corresponding lower Transmitter Power: https://imageevent.com/holl_ands/omni
FYI: BPR-3, Para 7.4 indicates that typical range of VLPFM (Very Low Power FM, 10-W Max ERP) is just 2 km....which may or may NOT meet your needs, in which case you might want to look at LPFM (Low Power FM, 50-W Max ERP), which is limited by Line-Of-Sight, with a range that MIGHT be as much as 10's of km's.
You/We should investigate these claims a bit further, esp. since your viewers would be using a variety of FM Radios with Sensitivity ranging from Good to Poor, esp. given that most would NOT be using even Mediocre Indoor Antennas, such as Rabbit Ears or a (two-arms-length) Folded-Dipole....and few would want to install an Outdoor Antenna. [And bear in mind that Antenna Gain for a typical Indoor FM Radio is significantly NEGATIVE due to it's size....and typical Indoor Loss MIGHT be as high as 20 dB.]
For comparison, FCC estimates that a 100-W ERP LPFM Station (in US) would have a "service range" of just 5.6-km [which would INCLUDE a predominance of Listeners with Indoor Radio/Antennas]: https://www.fcc.gov/media/radio/lpfm
You should contact OTHER Religious Broadcasters in your area to build on their experience. I tried to find some GROUPS that could help you, but didn't immediately find any in your area. However, I did find the fol. [somewhat out of date] re. Special "Balance" Rules for Licensed Religious Broadcasters, which you MAY need to know (esp. HOW to meet the "Balance" Rules): https://www.queensu.ca/lawjournal/si.../8-Faassen.pdf
The university here had a 50W ERP transmitter for some time. (It's now higher.) The antenna was on a short tower above a high rise so elevation was probably about 100'-150' above local terrain. On a car radio it was easily receivable up to about 10km, a little further outside the city with good terrain. In the city, household radios with a builtin antenna were fair to marginal at about 5km.
, their are not a lot of religious broadcasters in Canada. The ones near here have regular broadcast licenses and are fairly commercial in that they sell air time to advertisers and religious groups. It's not like the US which has evangelical groups with their own stations.