A lot of the countries in Europe are now accepting credit cards for payment for use of bathrooms while out and about or on tours.  I also think that some countries are slower to accept credit cards and are still takaing cash only - probably moreso in Hungary and Bulgaria to name a few.  To be on the safe side, I think I'd be carrying both in case you need them.

However, Even the public toilets have machines that take coins and also credit cards for a €.70 entry.  

If you’re in a city in the Netherlands and want a clean bathroom, the HEMA stores have them (usually on the second level) and their machines accept cards. In Rotterdam,  the central market has them on -1 (they boast over 100 toilets) and the machines accept cards too.

This TSA announcement just came out the other day - however, I would check with the official TSA site prior to travel to make sure things have not changed.  These dozen or so items will no longer be impacted by the TSA’s 3.4-ounce restriction, especially those that might be medically necessary according to the agency.First, breast milk, infant formula and even pouches of puree food can be packed in a carry-on bag and will not need to be packed in a quart sized bag.
In addition, accessories used to keep these things cold, like ice packs and freezer gel packs, in any state of being frozen.
The TSA warns that travelers should inform the security officer of the presence of infant food and remove it from the carry-on for seperate screening.
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Medications will also be exempt from the rule, along with any necessary accessories.
Newly allowed items include:

• Non-prescription medications
• Prescription medications in gel, liquid or aerosol form
• Ice packs or gel packs for medically necessary items
• Breast milk, formula, or baby food
• Liquid-filled teething aides
• Nasal sprays and saline
• Artificial tears, eye drops, and contact lens solution
• Non-flammable deodorant spray
• Liquid for dental prostheses
• Medical creams and lotions

When you’re traveling within the United States, we recommend that you arrive at the airport at least 2 hours prior to departure. All customers are required to be at the gate and ready to board 15 minutes before scheduled departure.
If you are traveling domestically and not checking baggage, you must be checked in at least 30 minutes before your scheduled departure time. For most airports, you must be checked in at least 30 minutes before your scheduled departure time.
For travel on or after April 8, 2025, baggage must be checked-in at least 45 minutes before your scheduled departure time. Airports requiring additional time are listed below
If you are traveling internationally, please review the international check-in requirements.  (Uusually 3 hours prior to travel)
Bags may be added to your reservation at the time of check-in. However, checked bags will not be accepted at the airport more than 6 hours prior to scheduled departure time.

Also - International Travel - I strongly suggest at least 2-1/2 hours for a layover and recommend to my clients at least 2-1/2 to 3 especially at major international (BIG) airports like Paris, Amsterdam and London/Heathrow - been through all 3 many times and personally know of whereof I speak.