Seeking any help or pointers I can get for additional records for G1 individual, worried what I have is insufficient

Hi, I found this sub on the sidebar of r/canadiancitizenship. Here is the information I have thus far, and I am wondering if anyone could give me any pointers on this. I think there is likely something out there that may not be available in the online search options i've utilized thus far. If anyone thinks they can further help here, I am more than happy to provide details of the individuals. I copied most of this from a comment on the pinned Friday Application assistance post in r/canadiancitizenship and adapted it to be a bit more readable for this subreddit.

I am able to take more questions from here, am happy to share the personal details of these individuals but would prefer to do this all over private messages only.

Here are the copies of records I have found for the G0 and G1 individuals

G0, female, Born 1889 in Toronto:
* Baptismal record archival scan
* marriage certificate w/ US born husband, Feb 1916, issued in Toronto

G1, male, born Dec 1917, USA.
* copies of 1921 and 1931 Canadian Census records, both in Toronto, (showing both G1 and G0), show birthplace as USA on both and immigration years of 1918 on 1921 census and 1917 on 1931 census. The ages reported on these support a 1917 birth year.

* Social Security Application SS-5 show Mother's name, and birthplace - I believe this will not be something I can order a copy of though, given that he is not >120 and I have not been able to locate a death record for him. This document reports birth year as 1912.

* US WWII draft card featuring G0/mother's name and address in Michigan; and city, state birthplace- 1942 - I found a copy of 1940 US census supporting G0/mother's address on the draft card, and the household matches up with the 1921 and 1931 Canadian censuses from Toronto (G0, husband, and G1's Canadian born brother) This document reports birth year as 1912.

* daughter's (G2) birth certificate - 1946 (still waiting on this document to arrive in the mail, expected Monday or Tuesday, will update with info from this once I see it)

* 1950 US census (showing G1 and G2)

Notes :
* G1's middle name is his mother's maiden name, not a particularly common name. This is shown on 1931 Canadian census record, SS-5, and the WWII draft card

* G1 put a different birth year, 1912, on official documents as an adult, such as social security and the aforementioned WWII draft card.

* I think the death record is maybe a dead end, as from what I was told growing up by G2, he went to Mexico in the 1980s for sham medical treatments and died there from it, so not sure about any death records. No obituary was able to be located either.

* For birth location, I'm not entirely sure how accurate the city and state reported on the SS-5 and Draft cards are. I was unable to find any report of this birth on any online sources to use for searching; the location reported on these documents is rural, so i wonder if it a record of birth was never filed.

* I know the date of marriage to G2's mother based on a found newspaper article related their divorce; but I cannot figure out where the marriage was filled/occurred, only thing is I've likely ruled out it happened in the county they lived in.

* I was suggested to look for a baptismal record for G1 in Toronto, not sure how to find this, as I happened across the G0 baptismal record on Family Search and didn't search for it on my own, so I'm not sure how to search for this for G1.

* I've not been able to locate immigration information and think this is also a potential lead, pointers here on where/what to search would be great too!

My main thing is that I'm not sure if what I have here is sufficient, I worry it isn't or optimistically is too borderline for comfort. Any pointers even would be greatly helpful. If you seriously think you can help me locate something, I can share relevant details and copies of the documents I've mentioned here for this search.

Here's a summary timeline based on the info I have here:
G0 (female) b 1889 - Toronto
G0 marriage 1916 - Toronto
G1 born 1917 - United States
G1 migration to Canada 1917 or 1918 (Canadian Census 1921 and 1931)
G1 files US social security application 1938
G1 WWII draft card 1942