How long to clear security upon arriving at Dublin Airport?

No way you’ll make Ryanair’s strict check-in cut off times. They have a weird document check rule, too.

I too think you’ll need to book a much later flight on some airline to get you to Bruges or Brussels. Check skyscanner.com for options, look carefully at the baggage allowances/fees and book directly with the airline. I’d consider the ticket you already have as a throwaway ticket.

Had you purchased this as one ticket you would not have to clear immigration in Dublin and could have just gone to your next gate. However since it's 2 separate tickets you have to clear immigration, clear customs and go through security again. No way it's going to happen.

I see that a later in the day ticket on Aer Lingus is $$$ but with Dublin hotels also being $$$, I think you are going to just have to get out the credit card and pay the price. There are flights available at 11:45 am and 6:45 pm for 200€ On Aer Lingus.

I agree with the other posters that you’re very unlikely to make the Dublin-Charleroi flight. If you fly with hand luggage only, you may have a chance because you can stay airside at Dublin Airport.
When you rebook a ticket, I would strongly recommend you to fly into a different airport. If your end destination is Bruges then Charleroi really isn’t a convenient airport to arrive at. It’s not served by trains, so you would first need to take a bus to Brussels and then transfer to a train to Bruges. Brussels Airport does have a train station and is therefore much more convenient.

The Bag Drop desks close strictly 40 minutes before the scheduled time of departure. If you miss this deadline your booking could be cancelled without refund and you could be prevented from boarding the plane.

It’s important that you make it to your boarding gate in good time, at least 30 minutes before your flight departure time.

Boarding closes 20 minutes before departure. Please have your valid travel document and boarding pass ready at the boarding gate. https://help.ryanair.com/hc/en-ie/articles/360017824898-Airport-Timeframes

I suspect the odds of your making the flight are the same as Satan getting a glass of ice-water

Should I prepare to find another way to get from Dublin to Bruges?

Yes, do it now, not the morning of the 19th.

RyanAir has a separate desk near check-in for this mandatory process: https://help.ryanair.com/hc/en-us/articles/360017683237-Non-EU-EEA-Passengers-Visa-Check#:~:text=Irrespective%20of%20a%20passenger's%20visa,before%20going%20through%20airport%20security.

thanks for the help everyone.

I'm going to salvage the day by flying to cologne on a 12:35 noon flight (a bit less than 4 hrs after landing in dublin), and then taking a train to bruges. In between landing in Cologne and taking the train I might visit the Cologne Cathedral. All in all an extra $200 spent and a wasted ryanair ticket, but not the end of the world, and I'm very glad I discovered my error now rather than in Dublin Airport on August 19th at 9:50am!

It was good to have that insight now rather than next Friday for sure! You made workable recovery for a first time international traveler. Now go enjoy your trip!