I am sorry to hear about your loss and situation. I would suggest the following industry-known expert Pamela Morgan (She is the partner of Bitcoin advocate Andreas Antonopoulos) on the matter of estate-related crypto planning and backups, and who could potentially help guide you in the recovery process (here is her official Twitter and Website for reference).
I am not endorsing her and suggest you do your own research, but I am just sharing who I think would be most knowledgable on how to approach this topic the most carefully and whom I would personally trust.
Caution:
I would not share any of the information with anyone, as any private-key or recovery-phrase related information would be the equivalent of giving someone cash that you cannot recover if they turn out to be malicious.
Information gathering:
I would continue to aggregate the information you have to build a map of all the account and wallets and associated login info, whether associated with emails, phone numbers, and be on the lookout for any paper backups where you might see 12 or 24 words written in order that are spelled correctly but the sentence doesn't seem to make sense, as those are mnemonic backups of crypto vault, where there could be multiple cryptocurrencies associated (as per BIP44), and multiple addresses (as per BIP32) per each support asset.
Here are examples of a random 12-word mnemonic:
position solution half fly topic large scene verify moment boost catch push
There could also be keystore files (usually .json files) that have UTC and a date in the filename, which are AES-ciphertext and would require a password to decrypt (and would likely contain a private key or recovery phrase). Those json files have a filename that looks like this:
UTC--2019-08-15T20-56-......
There could be notes that were kept of pin codes or passwords elsewhere, whether in a note pad or word document or password manager.
Note: Take great care to keep any such backups secret and not to share those words with anyone and keep them offline, until you can find the help you need.
Custodial and non-custodial brokers/exchanges/wallets: Knowing what types of applications were installed and what brokerage accounts were used will also help determine whether the accounts were non-custodial, or if the brokerage/wallet provider has access to the funds as well (in which case you could reach them for next steps) whereas, the non-custodial providers do not have access to the funds but at most could provide any information that was associated with the account in some cases. Good luck~
