I'm going to tag @crohnsinct
since her daughter has very refractory Crohn's, which started off only in her colon.
There are a lot of options. Honestly, my daughter's GIs - both pediatric and adult - told us that they have had better results with Remicade and Humira than with Stelara and Entyvio for Crohn's. My daughter's pediatric GI said Entyvio (in her experience) was a "weaker" biologic and it also was a slow acting biologic. My daughter was on it (briefly) and she said to give it 6 months to work. In contrast, Remicade and Humira work much faster, and with especially with Remicade, you have a lot more flexibility with the dosing and the frequency. You could start at 5 mg/kg every 8 weeks and increase it to as often as every 4 weeks. And the dose can vary from 5 mg/kg - 10 mg/kg, though sometimes doctors will go higher - my daughter went up to 20 mg/kg every 4 weeks.
Typically Remicade is the biologic used first for severe Crohn's, though of course you can certainly start with Stelara or Humira or Entyvio. Plus, you can also add an immunomodulator like Methotrexate to give any of the biologics "a boost," though it's done most often with Remicade and Humira.
Besides those biologics, Cimzia and Simponi are other anti-TNFs used for IBD. Xeljanz and Rinvoq are a JAK inhibitors approved for UC, and Rinvoq is doing very well in Crohn's studies too. My daughter has been on it (it was prescribed for her psoriatic arthritis which is how we got it approved). JAK inhibitors are pills which is a plus for some - I know you mentioned one of your sons had issues with injecting himself.
There are also other drugs in trials - similar to Stelara, Tremfya and Skyrizi are IL-23 inhibitors (Stelara is an IL-23 and IL12 inhibitor, so it's a bit different). Skyrizi has been filed for approval and Tremfya is still in trials for both UC and Crohn's.
There are also trials using two biologics together - such as Remicade and Entyvio for example. My daughter has severe inflammatory arthritis so she has been on two biologics for years now (almost 5 years) - in her case, one for the Crohn's and one for the arthritis. But GIs do occasionally use two biologics just for Crohn's - again, @crohnsinct
's daughter was on Entyvio and Humira for a while. There are more studies being done on dual biologics now.
There are also other drugs used occasionally - stronger immunosuppressants like Tacrolimus. And there are plenty still in early trials.
Surgery is also an option. TPN or EEN are options to help a biologic kick in, as are steroids.
I honestly would not worry about your child not responding to any biologic at all. I've been on this forum for a long time (well, the parents' forum) - 9 years or so. And very few kids didn't respond to anything. I wouldn't worry if it's only been 10 weeks with Entyvio - you may need to wait longer or he may need infusions more frequently before you can say it isn't working at all.